Monica’s school band held a car wash to raise money for a trip to a parade in new york city. after washing 125 cars, they made $775 from a combination of $5.00 quick washes and $8.00 premium washes.

let x represent the number of quick washes and let y represent the number of premium washes. which system of linear equations represents the situation?
5x + 8y = 775 and x + y =125
5x – 8y = 125 and x + y = 775
5x + 8y = 775 and x – y = 125
5x – 8y = 125 and x – y = 775

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