If y varies inversely as x and x=7 when y=21, find y when x=42.

Ahigh definition tv cost $800 with a down payment of 2/5 of the cost. how much is left to pay, in dollars after the down payment has been made?

The ratio of rock songs to dance songs on jonathan’s mp3 player is 5: 6. the total number of rock and dance songs jonathan has is between 101 120. how many rock songs does he have?

Suppose that 3% of all athletes are using the endurance-enhancing hormone epo (you should be able to simply compute the percentage of all athletes that are not using epo). for our purposes, a “positive” test result is one that indicates presence of epo in an athlete’s bloodstream. the probability of a positive result, given the presence of epo is .99. the probability of a negative result, when epo is not present, is .90. what is the probability that a randomly selected athlete tests positive for epo? 0.0297