Hi I dont really get the following so thanks if anyone could help:

A biased cubical die has faces numbered 1, 2, 3, 4, 5, 6 and X denotes the number obtained when the die is tossed once with probabilities P(X = x) = kx^2.

Find the value of k.

Ten independent observations of X are taken. Find the probability that there is exactly four times when the result is at least 5.