There are 10 students in a class: 5 boys and 5 girls. if the teacher picks a group of 3 at random, what is the probability that everyone in the group is a boy?

On a string instrument, the length of a string varies inversely as the frequency of its vibrations. an 11-inch string has a frequency of 400 cylces per second. find the frequency of a 10-icnch string.

Elena is paid a constant rate for each hour she works. the table shows the amounts of money that elena earned for various amounts of time that she worked.

*segment an is an altitude of right ? abc with a right angle at a. if ab = 2root 5 in and nc = 1 in, find bn, an, ac.