Ok, I completely useles at probability and stats and don't understand these questions.

Computer parts are exponentially distributed and have a mean lifetime of 1000 hours, and are independent of each other.

What proportion are in excess of 100 hours?

Boxed in packages of 10, each box is to have at least 9 in excess of 100 hours. Calculate the percentage?

Also gold coins are found 1 per 1km sq. Jim has a metal detector and searches 10km sq.

Let N be the number of coins in that area. State the distribution X.

And the probability of finding a coin is 0.6. Let X be the number of coins found and N=n, what is the distribution of X. The calculate the mean of this distribution.

Is it a Poisson distribution?