A fitness club set up an express exercise circuit. To warm up, a person works out on weight machines for 90 s. Next the person jogs in place for 60 s, and
then takes 30 s to do aerobics. After this, the cycle repeats. If you enter the
express exercise circuit at a random time, what is the probability that a friend
of yours is jogging in place? What is the probability that your friend will be on
the weight machines?