A computer sales store purchased 3 machines from a manufacturer. He will sell them for 1000 each. The manufacturer promised to buy back any unsold computers after 6 months for 200 each For the store, the acquisition cost of each machine is 600. Let X be the number of computers sold and their corresponding probabilities: a) Calculate expected profit b) Calculate the coefficient of variation. c) It would be better to buy 2 machines instead of 3. Why?

Bianca buys a bag of cookies that contains 9 chocolate chip cookies, 6 peanut butter cookies, 6 sugar cookies and 7 oatmeal cookies. What is the probability that Bianca randomly selects an oatmeal cookie from the bag, eats it, then randomly selects a chocolate chip cookie? Express you answer as a reduced fraction.

Sam wants to take his music player and his video game player on a car trip. An hour before they planned to leave, he realized that he forgot to charge the batteries last night. At that point, he plugged in both devices so they can charge if possible before they leave. Sam knows that his music player has 40% of its battery life left and that the battery charges by an additional 12 percentage points every 15 minutes. His video game player is new, so Sam doesn’t know how fast it is charging but he recorded the battery charge for the first 30 minutes after he plugged it in. a. If Sam’s family leaves as planned, what percent of the battery will be charged for each of the two devices when they leave?

If we have a score of 100 and is 20% of the grade and a score of 89 which is 40%.  What is my grade?