Question

Two boxes contain tokens on which numbers 1, 2, 3, 4 are written One token is taken from each box. What is the probability of getting sum of the face numbers a prime number

Answer 1

Pairs of numbers in tokens are (1.1) , (1,2), (1,3), (1,4) (2.1), (2, 2), (2, 3), (2, 4) (3, 1), (3,2), (3; 3), (3,4) (4, 1), (4, 2), (4, 3), (4,4).

Pairs getting sum as prime numbers (1.1) , (1,2), (1,4), (2, 1), (2, 3), (3, 2), (3, 4), (4, 1), (4, 3) 

Probability of getting sum of the face numbers a prime number = \(\frac{9}{16}\)