find the probablity

Question

 

1. The probability of a newly generated virus attacked to the computer system will corrupt the 4 files out of 20 files which are opened in an hour . If 20 files are opened in an hour , find the probability that (i) at least 10 files are corrupted (ii)Exactly 3 files are corrupted (iii)all files are corrupted (iv)all files are safe (v)more than 2 but not more than 5 files are corrupted.

Answer 1

this should be asked by a teacher