CBQs Ch- 13 Surface area and volume - Maths Class 9th 1 . Dev was doing an experiment to find the radius r of a sphere.For this he took a cylindrical container with radius R = 7 cm and height 10 cm. He filled the container almost half by water as shown in the left figure. Now he dropped the yellow sphere in the container. Now he observed as shown in the right figure the water level in the container raised from A to B equal to 3.40 cmi. What is the approximate radius of the sphere? a. 7 cm b. 5 cm c. 4 cm d. 3 cm ii. What is the volume of the cylinder? a. 700 cm³ b. 500 cm³ c. 1540 cm³ d. 2000 cm³ iii. What is the volume of the sphere? a. 700 cm³ b. 600 cm³ c. 500 cm³ d. 523.8 cm³ iv. How many litres water can be filled in the full container?( Take 1 litre=1000 cm³) a. 1.50 b. 1.44 c. 1.54 d. 2 v. What is the surface area of the sphere? a. 314.3 m² b. 300 m² c. 400 m² d. 350 m² 1.) b.5cm 2.) c.1540cm² 3.) d.523.8cm³ 4.) c.1.54 5.) a. 314.3m² 2 . A conical circus tent has to be made with a cloth that is 5m wide, whose height is 24m, and the radius of the base is 7m. 1. How many 'meters of cloth is required for making the tent' comes under which concept 2. Find the length of the cloth used to make the tent 3. Find the cost of cloth at Rs.7per m². 4. Find the Curved Surface Area Answers: 1. Curved Surface Area 2. 550 m 3. Rs.3850 4.110m² 3 . Once four friends Rahul, Arun, Ajay, and Vijay went for a picnic at a hill station. 'Due to peak season, they did not get a proper Hotel in the city. The weather was fine so they decided to make a conical tent at a park. They were carrying 200 sq.m cloth with them. They made the conical tent with a height of 8m and a diameter of 12m. The remaining cloth was used for the floor I) What is the slant height of the tent? ii) How much cloth was used for the floor? iii) What was the volume of the tent? iv) What was the area of the floor? v) What was the total surface area of the tent? Solution : Given : 200 sq.m cloth used to make tent ,. conical tent with height 8m and diameter 12m. The remaining cloth was used for the floorTo find : i) What is the slant height of the tent? ii) How much cloth was used for the floor? iii) What was the volume of the tent? iv) What was the area of the floor? Solution: conical tent with height 8m and diameter 12m. => radius = 12/2 = 6 m h = 8 m slant height L = √6² + 8² = 10 m slant height of the tent = 10 m Lateral surface Area = πRL = π ( 6) ( 10) = 60π = 60 x 3.14 = 188.4 m² cloth used for the floor = 200 - 188.4 = 11.6 m² volume of the tent = (1/3)πR²h = (1/3)(3.14)*6²*8 = 301.44 m³ area of the floor = πR² = 3.14 (6)² = 113.04 m²