If the boat goes 21 km downstream, What is the time required to cover it?
a) 5 hrs
b) 2 hrs
c) 7 hrs
d) 3 hrs

1 Answer

Answer :

d) 3 hrs

Related questions

Description : A boat goes 30 km upstream and 44 km downstream in 10 hours. In 13 hours it can go 40 km upstream and 55 km downstream. Then what is the speed of the stream? (a) 3km/hr (b) 5km/hr (c) 6km/hr (d) 7km/hr

Last Answer : (a) 3km/hr

Description : A boat goes 30 km upstream and 44 km downstream in 10 hours. In 13 hours it can go 40 km upstream and 55 km downstream. Then what is the speed of the stream? (a) 3km/hr (b) 5km/hr (c) 6km/hr (d) 7km/hr

Last Answer : (a) 3km/hr

Description : A boat man lakes 5hrs 30 mins to row a boat 30km downstream of a river and 4 hrs 15mints to cover a distance of 10km upstream. Find the speed of the river current in km/hr. A) 1.5 km/hr B) 3km/hr C) 5km/hr D) 7 km/hr

Last Answer : ANSWER: A  Explanation:  Rate downstream = (30 / 5 ½ ) km/hr  = 30 / (11/2) km/hr  = 30 * 2 / 11 km/hr = 60/11 km/hr  Rate upstream = (10 / 4 ¼)km/hr  = 10 / (17/4)km/hr  = 10 * 4 / 17 km/hr = ...  Speed of current = 1 / 2 (a - b) km/hr  =1 / 2 (60 / 11 - 40 / 17)  = 1.5 km/hr (approx.)

Description : A boat is rowed downstream at 15.5 km/h and upstream at 8.5 km/h. The speed of the stream is: (a) 3.5 km/h (b) 5.75 km/h (c) 6.5 km/h (d) 7 km/h

Last Answer : (a) 3.5 km/h

Description : If the speed of the boat is 5 km/hr and the speed of stream is 2 km/hr, what is the speed of the boat Downstream? a) 5km/hr b) 2km/hr c) 7km/hr d) 3km/hr

Last Answer : c) 7km/hr

Description : A motorboat running upstream takes 4 hrs 24 mins to cover a certain distance, while it takes 2hrs to cover the same distance running downstream. What is the ratio between the speed of the boat and speed of the water current respectively? A) 8:3 B) 5:2 C) 3:7 D) 2:4

Last Answer : ANSWER : A Explanation: Let the man's rate upstream be x'km/hr and downstream be y'km/hr Then distance covered upstream by 4hrs 24mints = distance covered by downstream in 2hrs (x * 4 2/5) = y *2 22x/5 = 2y Y = ... = (y+x/2) : (y -x/2) = 16x/10 : 6x/10 = 16x : 6x = 8:3

Description : A boat covers 12 km upstream and 18km downstream in 3hrs while it covers 18 km upstream and 12km downstream in 3 ¼ hrs the velocity of the the boat upstream and downstream? A) 4,8 B) 8,12 C) 12,16 D) 3,9 

Last Answer : ANSWER : B 

Description : A boat takes 38 hrs for travelling downstream from point p to point q and coming back to a point r midway between p and q. If the velocity of the stream is 8 km/hr and the speed of the boat in still water is 28 km/hr. What is the distance between p and q? A) 720 B) 640 C) 510 D) 450

Last Answer : ANSWER: A Explanation: Speed downstream = (28 + 8)km/hr = 36 km/hr Speed upstream = (28 – 8)km/hr = 20 km/hr Let the distance between p and q be ‘x’km Then, x/36 + (x/2)/20 = 38 x/36 +x/40 = 38 19x = 13680 X = 720 km Therefore the distance between p and q is 720km

Description : A pedal boat goes 12km upstream and 14km downstream in 3hrs. It goes 15km upstream and 10.5km downstream in 3 hrs 15mints. The speed of the boat in still water is A) 10 B) 15 C) 20 D) 25 

Last Answer : ANSWER: A

Description : A boat travels 20 kms upstream in 6 hours and 18 kms downstream in 4 hours. Find the speed of the boat in still water and the speed of the water current? (a) 1/2 kmph (b) 7/12 kmph (c) 5 kmph (d) none of these

Last Answer : (b) 7/12 kmph

Description : A boat takes 24 hours to cover 128 km downstream and 16 hours to cover 64 km upstream. Then the speed of the boat in still water is: A) 14/3 B) 8/7 C) 3/2 D) 9/5

Last Answer : Answer: A Explanation: Distance covered in downstream = 128km Time taken in downstream = 24 hours. Rate of downstream = distance / time = a = 128 km /24 hours = 16/3km/hr Distance covered in upstream = 64km Time taken in upstream ... / 2 = (1/2)(16/3+4) km/hr = (1/2)(28/3)km/hr = 14/3km/hr.

Description : A motor boat sails 30 km of a river towards upstream in 10hrs. How long will it take to cover the same distance downstream, if the speed of the current is ½ of the speed of the boat in still water. A) 1.8hrs B) 3.33hrs C) 5hrs D) None of these

Last Answer : ANSWER : B  Explanation:  Upstream speed = x –y  Downstream speed = x + y  x– y = 30/10 = 3km/hr  Again x = 2y  Therefore x – y = 3  y= 3km/hr ; x = 6km/hr  Therefore x + y = 9 km/hr  Time during downstream = 30/9 = 3.33hrs

Description : A boat takes 27 hrs to travel a distance upstream and takes 9hrs to travel the same distance downstream. If the speed of the boat in still water is 12km/hr, then what is the velocity of the stream? A) 8km/hr B) 6km/hr C) 4km/hr D) None of these

Last Answer : ANSWER : B  Explanation: Let the velocity of the stream be ‘ y’ km/hr Then the speed of the downstream = (12 + y)km/hr The speed of the upstream = (12 – y)km/hr 9 (12 + y) = 27 (12 – y) 108 + 9y = 324 – 27y 27y + 9y = 324 - 108 36y = 216 y = 6 km/hr

Description : If the speed of boat is 5 km/hr and speed of stream is 2 km/hr. What is the speed of the boat in Upstream? a) 5km/hr b) 2km/hr c) 7km/hr d) 3km/hr

Last Answer : d) 3km/hr

Description : A boat takes 4hours for traveling downstream from point P to point Q and coming back to point P upstream. If the velocity of the stream is 2km ph and the speed of the boat in still water is 4kmph, what is the distance between P and Q? A.9 km B.7 km C.5 km D.6km

Last Answer : Answer- D Basic Formula: Speed of stream = ½ (a-b) km/hr Speed of still water = ½ (a+b) km/hr Explanation: Time taken by boat to travel upstream and downstream = 4 hours Velocity of the stream, ½ (a-b) = 2km/hr a ... + x / 6 = 4 3x + x / 6 = 4 4x = 24 so,x = 6 distance between P and Q = 6km

Description : Thirty men take 20 days to complete a job working 9 hours a day. How many hour a day should 40 men work to complete the job? (a) 8 hrs (b) 7 1/2 hrs (c) 7 hrs (d) 9 hrs

Last Answer : (b) 7 1/2 hrs

Description : A boat running downstream covers a distance of 20 km in 5 hours while for covering the same distance upstream, it takes 10 hours. What is the speed of the stream? a) 2km/hr b) 4km/hr c) 1km/hr d) 1.5 km/hr e) None of these

Last Answer : c Rate of downstream=(20 / 5 ) kmph= 4kmph Rate of upstream =( 20/10) kmph= 2kmph Therefore Speed of the stream= (1/2)(4 - 2) kmph= 1 kmph

Description : A motor boat whose speed is 18 km/h in still water takes 1 hour more to go 24 km upstream than to return downstream to the same spot. Find the speed of the stream. -Maths 10th

Last Answer : The given speed of the motor boat in the still water is equal to 18 km/ hr. The given distance travelled by motor boat is equal to 24 km. The time taken to travel 24 km downstream by motor boat = 1 hour. x=122=6 km/ hr.

Description :  Sakthi rows a boat at 4 km upstream in 1hour and 1 km downstream in 20 minutes. How long will he take to reach 3.5km in still water? A) 1 B) 2 C) 3 D) 4

Last Answer : ANSWER:A Explanation: Upstream Speed = 4/1 = 4km/hr Downstream Speed = 1/20 = 0.05 km/min = 0.05*60 = 3 km/hr Hence, speed of boat = 1/2( Upstream Speed + Downstream Speed) = 1/2 (4+3 ... , the time required to reach the distance of 3.5 km=DistanceCovered/Speed of boat = 3.5/3.5km/hr =1 km/hr

Description : A royal enfield bike starts with the speed of 210 km/hr with its speed increasing every 2 hrs by 30km/hr, in how many hrs will it cover 1035km? a) 2 1/2 hr b) 4 1 /2 hr c) 6 1 /2 hr d) 7 1 /2 hr

Last Answer : B Distance covered in 1st 2 hrs = (210*2)km =420km Distance covered in next 2 hrs = (240*2)km =480km Remaining distance = 1035 – (420+480) =1035 – 900 =135km Speed in 5th hr = 270 km/hr Time taken to cover 135 km = 135/270 = ½ hr Total time taken = (2+2+1/2) =4 ½ hrs

Description : A man takes 10 hours to cover a distance while traveling upstream on a boat, whereas while traveling downstream it takes 6 hours. If the speed of the boat in still water is 6 kmph, what is the speed of the stream? 1 : 2.5 kmph 2 : 2.2 kmph 3 : 2 kmph 4 : 1.5 kmph 5 : None of these

Last Answer : 4 : 1.5 kmph

Description : A boat cover a certain distance downstream in 2hr while it comeback 3/2hrs.If the speed of the stream be 4kmph.what is the speed of the boat in still water? 1)21kmph 2)18kmph 3)22kmph 4)12kmph

Last Answer : 1)21kmph Exp:(x+3) ×2=(x-3)(3/2)=>21.

Description : Mohana can row 80km upstream and 110km downstream in 26 hrs. Also she can 60km upstream and 88km downstream in 20 hrs. Find the speed of the girl in still water and the speed of the current in ratio: A) 5:6 B) 3:6 C) 7:9 D) 8:3 

Last Answer : ANSWER : D Explanation: Let rate upstream = x' km/hr and  Rate downstream = y' km/hr  Then 80/x + 110/y = 26 ---1  60/x + 88/y = 20--2  By solving 1 and 2  y= 11 ; x = 5  Rain in still water ... 5) km/hr = 8 km/hr  Rain of current = ½ (11 - 50) km/hr = 3 km/hr  The required answer is 8:3

Description : A pedal boat can cover 20km in 1 hr in still water. And it takes thrice as much as time to cover up than as to cover down the same distance in running water. The speed of the current is. A) 7.5 km/hr B) 20 km/hr C) 5 km/hr D) 10 km/hr

Last Answer : ANSWER : D Explanation: Let the speed of upstream be x' km/hr Then speed in downstream = 3x km/hr[thrice as much as time to cover up than as to cover down the same distance in running water] Speed in ...  Speed in downstream = 30 km/hr  Hence speed of the current = (30 -10)/2  = 10 km/hr.

Description : A motor car starts with the speed of 70 km/hr with its speed increasing every two hours by 10 kmph. In how many hours will it cover 345 kms? A.4 hrs B.4 hrs 5 mins C.4 1/2 hrs D.2 hrs E.None of these

Last Answer : Answer - C (4 1/2 hrs) Explanation - Distance covered in first 2 hours = (70 x 2) km = 140 km Distance covered in next 2 hours = (80 x 2) km = 160 km Remaining distance = 345 - (140 + 160) = 45 km. Speed in the ... ..1 hr 45km .? ?=45/90hr=1/2hr Total time taken = 2 + 2 +1/2=4 (1/2)hrs

Description : A motorboat can cover 80 km upstream and 120 km downstream together in 26 hours. Also it can cover 100 km upstream and 144 km downstream together in 32 hours. What is the speed of the motorboat in still water? A) 12 km/hr B) 15km/hr C) 8.5km/hr D) 19km/hr 

Last Answer : ANSWER :C Explanation:  Upstream speed in both cases is 80 and 100.  Ratio is 80 : 100 = 8:10 = 4 : 5.  So let times in both cases be 4x and 5x  Downstream speed in both cases is 120 and 144 resp.  Ratio is ... 12 km/hr  So speed of boat = 1/2 * (5+12) =17/2km/hr  speed of boat = 8.5 km/hr

Description : If a boy rows 8 km downstream in 6 hours and 4 km upstream in 4 hours then how long will he take to cover 16 km in stationary (still) water? A) 8 B) 14 C) 22 D) 16 

Last Answer : Answer: B Explanation: Distance covered in downstream = 8 km Time taken in downstream = 6 hours. Rate of downstream = 8/6=4/3 km/hr Distance covered in upstream = 4 km Time taken in upstream = 4hours. ... 3+1) = 7/6km/hr Time Taken to cover 16 km in still water = 16*6/7=14hrs (approximately)

Description : A boat goes 3.5km upstream in 24 mins and the speed of the stream is 1.5km per hour, then the speed of the boat in still water is. A) 4.3 km/hr B) 7.4 km/hr C) 5.2km/hr D) 10.25km/hr

Last Answer : ANSWER: D  Explanation:  Speed of upstream = 3.5 / 24 km/min  = 3.5 / 24 * 60 km/hr = 8.75 km/hr  Speed of the stream = ½ (a - b)km/hr = 1.5 km/hr  1.5 = ½ ( a- 8.75)km/hr  a = 11.75 km/hr ... (a + b) km/hr  = ½ (11.75 + 8.75) = ½(20.5)  The speed of the boat in still water = 10.25 km/hr

Description : Shreya travel the first part of her journey at 160 kmph and the second part at 240 kmph and cover the total distance of 3840 km to her destination in 20 hours. How long did the first part of her journey last? a) 8 hrs b) 12 hrs c) 16 hrs d) 10 hrs

Last Answer : B The total time of journey = 20 hours. Let 'x' hours be the time that shreya travelled at 160 kmph Therefore, 20-x hours would be time that she travelled at 240 kmph. Hence, she would have covered x*160+( ... 20-x)*240 =3840 160x +4800-240x =3840 240x-160x=4800-3840 80x= 960 X=960/80=12 hrs

Description : All solutions of the linear equation 2x + 3y = 7 are also the solutions of equation (a) 5x + 6y = 13 (b) 4x + 6y = 11 (c) 6x + 9y = 7 (d) 6x + 9y = 21

Last Answer : (d) 6x + 9y = 21

Description : The fractions 7/11, 16/20, 21/22 when arranged in descending order is (1) 7/11,16/20,21/22 (2) 21/22,7/11,16/20 (3) 21/22,16/20,7/11 (4) 7/11,21/22,16/20

Last Answer : (3) 21/22,16/20,7/11

Description : Two persons of masses 55 kg and 65 kg respectively, are at the opposite ends of a boat. The length of the boat is 3.0 m and weighs 100 kg. The 55 kg man walks up to the 65 kg man and sits with him. If the boat is in still water the centre of mass of the system shifts by

Last Answer : (4) zero

Description : A boat covers 14 kms in upstream and 20 kms downstream in 7 hours. Also it covers 22 kms upstream and 34 kms downstream in 10 hours. Find the speed of the boat in still water and of that the stream. -Maths 9th

Last Answer : Given, The boat covers 14 km upstream and 20km downstream . at time 7 hours also cover 22km ups. and 34km dwn in10 hours total speed = total distance/total time :.total distance = 14+20+22+34=90km and total time=7+10= ... =90/17 => 5.294km/h => 5.294km/h the speed of boat in still water is 5.29 km/h

Description : There are 3 poles M, N and O in a straight line such that point N is equidistant from points M and O. A boat can travel from point M to O downstream in 6 hours and from N to M upstream in 4 hours. Find the ratio of boat in still water to speed of stream. A) 2:3 B) 7:1 C) 3:2 D) 1:7

Last Answer : ANSWER: B Explanation: Let speed in still water = x km/hr, of current = y km/hr Downstream speed = (x+y) km/hr Upstream speed = (x - y) km/hr Let MO = 2p km. So MN = NO = p km.  So 2p/(x+y) = 6 --------1  p/ ... - 2y) = 6x + 6y  8x - 8y = 6x +6y  2x = 14y  x/y = 14 / 2 = 7/1  x : y = 7 :1

Description : The area to be covered by Green Grass is: a) 4 square km b) 5 square km c) 9 square km d) 10 square km

Last Answer : a) 4 square km

Description : A boatman can take the same time to row6.5km downstream and 3.5km upstream. His speed in still water 2.5 km/hr. The speed of the stream is. A) 0.75 km/hr B) 2.5 km/hr C) 1.5km/hr D) 7.5km/hr

Last Answer : ANSWER: A Explanation: Given that the speed in still water = 2.5 km/hr Let the speed of the stream be x; km/hr speed in upstream = (2.5 - x)km/hr Then time taken to cover 6.5 km downstream = 6.5 / (2.5+x) ... 5x = 8.75 + 3.5x 10 x = 7.5 x = 0.75 km/hr The speed of the stream is 0.75 km/hr

Description : If diameter of a wheel is 1.26 m, what the distance covered in 500 revolutions? (a) 1.38 km (b) 4.64 km (c) 2.46 km (d) 1.98 km

Last Answer : (d) 1.98 km

Description : The radius of a right circular cone is 3 cm and its height is 4 cm. The curved surface of the cone will be (1) 12 sq. cm (2) 15 sq. cm (3) 18 sq. cm (4) 21 sq. cm

Last Answer : (2) 15 sq. cm

Description : A man can row 15 km/hr in still water. It takes him twice as long to row upstream as to row downstream. Find the rate of stream? a) 5 km/hr b) 10 km/hr c) 7.5 km/hr d) 6 km/hr e) 8 km/hr

Last Answer : Let the man’s upstream speed be x km/hour and downstream speed will be 2x km/hour Speed in still water = 1/2 (2x + x) = 3x/2 km/hour 3x/2 = 15 X = 10 Hence, his downstream speed = 20km/hour Rate of stream = 1/2 (20-10) = 5km/hour Answer: a)

Description : A boys rows to a certain place and comes back, but by mistake he covers 2/3rd more distance while coming back. The total time for this journey is 20 hours. The ratio of speed of boat to that of ... starting point from his present position? A) 2hr 13mints B)1hr 30 mins C) 2hr 30mins D)1hr 40 mins

Last Answer : ANSWER : A Explanation: let speed of boat and stream be 2x and x respectively So downstream speed = 2x+x = 3x, and upstream speed = 2x-x = x Let total distance between points is d km So he covered d ... with speed 3x = 48 km/hr(downstream) So time is 80/36 * 60 = 133.33 minutes = 2hr 13mins

Description : At the same speed a boat travelling 50km upstream and 78km downstream in 16hrs. Also it can travel 70km upstream and 104km downstream, in 22hrs at the same speed of the stream is. A) 5km/hr B) 3km/hr C) 4km/hr D) 2km/hr

Last Answer : ANSWER : C

Description : A diver rowing at the rate of 5 km/h in still water takes double the time in going 40 km upstream as in going 40 km downstream. Find the speed of the stream. -Maths 10th

Last Answer : 5/3 km/h Step-by-step explanation: Speed in still water = 5km/h Define x: Let the speed of the steam be x Upstream speed = (5 - x) km/h Downstream speed = (5 + x) km/h Time taken going upstream: Time taken = ... 40x = 400 - 80x 120x = 200 x = 200 120 = 5/3 The speed of the stream is 5/3 km/h

Description : Jackson travels a distance of 100km in 5 hrs. How much faster in kilometer per hr, on an average, must he travel to make a journey in 5/3 hr less time? a) 5 km/hr b) 10km/hr c) 6 km/hr d) 8 km/hr

Last Answer : B Time required = (5 hrs – 5/3 hrs) =(5 hrs – 100 mints) = (5 hrs – 1hr 40 mints) = 3 hrs 20 mints = 3 1/3 hrs Required speed = (100*3/10) km/hr =30 km/hr Original speed = (100/5)km/hr = 20 km/hr Difference speed = required speed – original speed =(30-20) =10km/hr

Description : If Nishu can swim downstream at 6kmph and upstream at 2kmph.What is his speed in still water ? A.5 km/hr B.4 km/hr C.8km/hr D.7km/hr

Last Answer : Answer- B Basic Formula: If the speed downloadstream is a km/ hr and the speed upstream is b km/ hr then Speed in still water is = ½ (a+b) km / hr [memory tool last 2 L cross and make +] Explanation: Given ... still water = ½ (a+b) kmph = ½ (6+2) = 8/2 = 4kmph speed in still water = 4kmph

Description : A mototboat can row to a place 112 km away and come back in 44 hours. The time to row 42 km with the stream is same as the time to row 24 km against the stream. Find the speed of boat in still water. A) 5.5 km/hr B) 7.5km/hr C) 10.5 km/hr D) 3.5 km/hr 

Last Answer : ANSWER: A Explanation: Downstream speed = 42/x km/hr Upstream speed = 24/x km/hr 112 / (42 / x) + 112 / (24 / x) = 44 112[x /42 + x / 24] = 44 112 / 3 [x / 14 + x / 8] = 44 11x / 56 = 44 * ... = 4 km/hr Speed of boat = 1/2 * (7 + 4) km/hr = 11 /2 speed of boat in still water = 5.5 km/hr

Description : A 1800 km journey of 24 hrs, if 360km is done by van and the rest by train. It takes 60 mins more, if 600km is done by van and the rest by train. The ratio of the speed of the van to that of the train is. a) 2:4 b) 4:3 c) 3:4 d) 5:3

Last Answer : C Let the speed of the van be x km/hr And that of the train be y km/hr 360/x+1440/y = 24 --------------->A Dividing by 24 on both sides 15/x+60/y = 1 ---------1 And 600/x +1200/y =25 Dividing by ... 720/y =9 Y=80 Put y value in A 360/x = 24-18 X=360/6 X=60 Ratio of speeds = 60:80 = 3:4

Description : Karthiga jogs a speed of 18 km/hr at a distance of 27 km. at what speed would she need to jog during the next 4.5 hrs to have an average of 27km/hr for the entire jogging session. a) 40km/hr b) 30 km/hr c) 20 km/hr d) 35 km/hr

Last Answer : B Let the speed of jagging be x km/hr Total time taken = (27/18 hrs + 4.5 hrs) =(1.5 hrs + 4.5 hrs) =6 hrs Total distance covered = (27+4.5 x) km Therefore (27 +4.5x) / 6= 27 27+4.5x = 162 4.5x = 135 X=135/4.5 =30 So jagging speed is 30 km/hr

Description : P,Q & R are on a journey by scorpio. P drives during the 1st 2 hrs at an average speed of 60 km/hr. Q drives during the next 3 hrs at an average speed of 58 km/hr R drives for the next 4 hrs at an average speed of 62 ... exactly 5 hrs. Their main speed is. a) 60 2/9 b) 62 2/9 c) 60 4/8 d) 62 4 /8 

Last Answer : A Distance covered by P = 2*60 = 120 km Distance covered by Q = 3* 58 = 174 km Distance covered by R = 4*62 = 248 km Total distance = (120+174+248)km =542 km Total time taken = 2+3+4 = 9 hrs Mean speed = diatance/ time =(542 / 9)km/hr =60 2/9 km/hr

Description : The average speed of a bus in the upward journey is 50% more than that in the return journey. The bus halts for 2 hrs on reaching the destination. The total time taken for the complete to and from trip is 34 hrs ... speed of the bus in the upward journey is. a) 63.24 b) 65.67 c) 63.49 d) 62.49

Last Answer : D Let the speed in return journey be x km/hr Then speed in upward journey = 150 /100 x = (3/2 x)km/hr Average speed = (2*3x/2*x) / (3x/2 +x) =3x2 / (5x/2) =6x2 / 5x =6x/5 km/hr Therefore (1600 ... 192x = 8000 X = 41.66 Speed in upward journey = (3/2 x ) km/hr =(3/2*41.66) =62.49 km/hr 

Description : Ashok can row upstream at 8kmph and downstream at 12kmph.What is the speed of the stream ? A.6km/hr B.3km/h C.2 km/hr D.4km/hr

Last Answer : Answer -C Basic Formula: If the speed downstream is a kmph and the speed upstream is b kmph then Speed of the stream = ½ (a-b) kmph Explanation: Speed downstream a = 12kmph Speed upstream b = 8 kmph Speed of the stream = ½ (a-b) = ½ (12-8) = 4/2 = 2 kmph speed of the stream = 2kmph