Processing math: 37%
Home / Aptitude Tests / Further Mathematics / A box contains 4 red...

A box contains 4 red and 3 blue identical balls. If two a...

A box contains 4 red and 3 blue identical balls. If two are picked at random, one after the other without replacement, find the probability that one is red and the other is blue.

A.

47

B.

27

C.

17

D.

112

Correct answer is A

P(one blue, other red) = P(1st red then blue) or P(1st blue then red)

= (47×36)+(37×46)

= 27+27=47