p_malh wrote:

**Quote:**

1) 1/4 * 1/4 *4 = 1/4

2) 1/4*1/4*1/4*4 = 1/16

Each anti air craft has 1/4 prob to be shooting at one plane, so 1/4*1/4 (two anti air craft). Then we multiply by 4 because we have 4 planes to choose

Mbao4,

Shouldn't the first one be multiplied by 6 instead of 4, since we have 4C2 ways to choose 2 planes out of 4?

Please explain

Before Mba answers, let me try.

Think about two planes separately: the probability that one is firing is 100% or 1 (appears from the question stem). Now, the P that the second gun is firing at the same plane as the first one is 1/4, is't it? - four planes - one gun - this should be clear.

Multiply to get the total P. 1*1/4=1/4

Gabish?

_________________

Respect,

KL