Find the length of KC

In triangle △abc, ∠abc=90°, bh is an altitude. find the missing lengths. ab=4 and bc=3, find ah, ch and bh.

Leo is going to use a random number generator 4 0 0 400 times. each time he uses it, he will get a 1 , 2 , 3 , 4 , 1,2,3,4, or 5 5. what is the best prediction for the number of times that leo will get an odd number?

Sole with work in 10 years, the average number of hours of tv watched per week by teenagers dropped from 23.9 to 21.4. find the percent of change.