Working at their respective constant rates, machine A makes 100 copies in 12 minutes and machine B makes 150 copies in 10 minutes. If these machines work simultaneously at their respective rates for 30 minutes, what is the total number of copies that they will produce?

Company P's cost c, in dollars, of producing n units of a certain product is c = 2.5n + 25,000. What is the greatest number of units that Company P can produce if the cost of producing these units cannot exceed $200,000 ?

For all numbers a and b, the operation # is defined by a # b = 2a + 2b + 1. What is the value of 6 # 1 ?

One morning Emily recorded the time that it took to read each of her e-mail messages. The times, in seconds, were 32, 18, 20, 29, and 21. How many seconds greater was the average (arithmetic mean) time than the median time?

In a class of 30 students, 2 students did not borrow any books from the library, 12 students each borrowed 1 book, 10 students each borrowed 2 books, and the rest of the students each borrowed at least 3 books. If the average (arithmetic mean) number of books borrowed per student was 2, what is the maximum number of books that any single student could have borrowed?

Each day Linda spends 6 hours at her baby-sitting job, for which she is paid $15.00 per hour. In addition, Linda spends a total of 1.5 hours each day, for which she is not paid, traveling to and from the job. What is Linda's hourly rate of pay for the total amount of time that she spends each day at her baby-sitting job and traveling to and from that job?

Denise made 9 sales calls on Monday, 6 sales calls on Tuesday, 7 sales calls on Wednesday, 9 sales calls on Thursday, and 11 sales calls on Friday. What was the average (arithmetic mean) number of sales calls that Denise made for these 5 days?

Helen, Jim, and Ivan each purchased some books at a bookstore. Helen purchased 4 books and Jim purchased 1 book. If the 3 people purchased an average (arithmetic mean) of 2 books per person, how many books did Ivan purchase?

According to a financial analyst, if Company C sets the unit selling price of its product at x dollars, then its monthly profit P, in dollars, is given by the formula ~$P=1000\left ( 4x-x^{2}-2 \right )$~. According to this formula, at what amount should Company C set the unit selling price of its product so that its monthly profit is $2,000 ?

If the probability that event S will not occur is 1 - y, then the probability that event S will occur is?