Two dice are rolled once. Find the probability of getting an even number on the first die, or a total of 7. -Maths 9th

1 Answer

Answer :

(c) \(rac{7}{12}\)Total number of ways in which 2 dice are rolled = 6 × 6 = 36 ⇒ n(S) = 36 Let A : Event of rolling an even number of 1st dice B : Event of rolling a total of 7 ⇒ A = {(2, 1), (2, 2)…, (2, 6), (4, 1), (4, 2) …, (4, 6), (6, 1), (6, 2), …, (6, 6)} and B = {(1, 6), (2, 5), (3, 4), (4, 3), (5, 2), (6, 1)} ⇒ n(A) = 3 × 6 = 18, n(B) = 6 ⇒ A ∩ B : Event of rolling an even number on 1st dice and a total of 7 ⇒ A ∩ B = {(2, 5), (4, 3), (6, 1)} ⇒ n(A ∩ B) = 3 ∴ P(A) = \(rac{n(A)}{n(S)}\) = \(rac{18}{36}\);  P(B) = \(rac{n(B)}{n(S)}\) = \(rac{6}{36}\); P(A\(\cap\)B) = \(rac{3}{36}\)⇒ P(A ∪ B) = P(Event of rolling an even number 1st dice or a total of 7) = P(A) + P(B) – P(A ∩ B)= \(rac{18}{36}\) + \(rac{6}{36}\) - \(rac{3}{36}\) = \(rac{21}{36}\) = \(rac{7}{12}\).

Related questions

Description : Two unbiased dice are rolled. Find the probability of getting a multiple of 2 on one die and a multiple of 3 on the other die ? -Maths 9th

Last Answer : When two unbiased dice are rolled, the possible out comes are∴ n(S) = 36 Let A : getting a multiple of 2 on one die and a multiple of 3 on the other die. ⇒ A = {(2, 3), (2, 6), (4, 3), (4, 6), (6, 3), (6, 6), (3, 2), ( ... (3, 6), (6, 2), (6, 4)} ⇒ n(A) = 11∴ P(A) = \(rac{n(A)}{n(S)} =rac{11}{36}.\)

Description : Two dice are rolled simultaneously. The probability of getting a multiple of 2 on one dice and a multiple of 3 on the other is -Maths 9th

Last Answer : (c) \(rac{11}{36}\)Total number of outcomes when two identical dice are rolled, n(S) = 6 6 = 36 Let A : Event of rolling a multiple of 2 on one die and a multiple of 3 on the other die ⇒ A = {(2, 3), (2, 6), (4, 3), (4, ... , 4), (3, 6)} ⇒ n(A) = 11 ∴ P(A) = \(rac{n(A)}{n(S)}\) = \(rac{11}{36}\).

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Last Answer : (d) \(rac{1}{36}\)Total number of outcomes when three identical dice are rolled, n(S) = 6 6 6 = 216 Let A : Event of rolling same number or each dice ⇒ A = {(1, 1, 1), (2, 2, 2), (3, 3, 3), (4, 4, 4), (5, 5, 5), ... 6)} ⇒ n(A) = 6 ∴ P(A) = \(rac{n(A)}{n(S)}\) = \(rac{6}{216}\) = \(rac{1}{36}\).

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Last Answer : Let A : Getting an odd number on first die; B : Getting a multiple of 3 on second die, thenA = {1, 3, 5}, B = {3, 6} ∴ P(A) = \(rac{3}{6}=rac{1}{2}\), P(B) = \(rac{2}{6}=rac{1}{3}\) ... B are independent∴ Required probability = P (A) . P (B) = \(rac{1}{2}\) x \(rac{1}{3}\) = \(rac{1}{6}\)

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Last Answer : This answer was deleted by our moderators...

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Description : Three fair coins are tossed simultaneously. Find the probability of getting more heads than the number of tails. -Maths 9th

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Description : A coin is tossed 500 times and we get Heads : 285 and tails : 215 times. When a coin is tossed at random, what is the probability of getting a. head? b. tail? -Maths 9th

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Last Answer : NEED ANSWER

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Last Answer : Solution of the question

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