Question

4 out of 15 apples are rotten. What is the probability that the 9th apple take out is the last rotten one

Answer 1

# Answer = 0.041

# Explainaton-

We want 9th apple to be last rotten apple. For this, the first 8 apples should have 3 rotten ones and remaining 5 good ones. This can be chosen in 4C3×11C5 ways.

We have to select 8 apples from 15 apples. This can be done in 15C8 ways.

9th apple is the only rotten one left, which can be selected in 1 way.

Total number of ways of selecting that 1 rotten apple from remaining 7 will be 7C1 ways.

Total probability = (4C3×11C5)/(15C8×7C1)

Total probability = (4×462)/(6435×7)

Total probability = 0.041

Hope this helps...