Originally Posted by

**Mathematicsfan** I came across this task, and I could not solve it furthermore.

Can anyone check my equation and help me solve it?

**-The probability to succeed in a random test is 0.8. It's known that if N people attending to the test the probability that all of them will succeed is 0.4096.**

A- Find N.

I was only able to do this equation (Bernouli's table)

$\displaystyle (N/K)*(0.8)^k*(0.2)$ $\displaystyle ^n^-K=0.4096$

Can anyone help me solving furthermore with this equation please.

that's ^n-k