• Numerical Ability - Permutation & Combination Or Probability
Question

Two dice are tossed. The probability that the total score is a prime number is: 

  • A) 1/6
  • B) 5/1 
  • C) 1/2 
  • D) 7/9 
  • E) None of these
Solution

Answer (E): None of these

Explanation:

Clearly, n(S) = (6 × 6) = 36

Let E = Event that the sum is a prime number.

Then = {(1, 1), (1, 2), (1, 4), (1, 6), (2, 1), (2, 3), (2, 5), (3, 2), (3, 4), (4, 1), (4, 3), (5,2), (5, 6), (6, 1), (6, 5)}

n(E) = 15

P(E) =n(E)/n(E) - 15/36 = 5/12.

Answer (E): None of these

Explanation:

Clearly, n(S) = (6 × 6) = 36

Let E = Event that the sum is a prime number.

Then = {(1, 1), (1, 2), (1, 4), (1, 6), (2, 1), (2, 3), (2, 5), (3, 2), (3, 4), (4, 1), (4, 3), (5,2), (5, 6), (6, 1), (6, 5)}

n(E) = 15

P(E) =n(E)/n(E) - 15/36 = 5/12.
Comments