What is 13.5+5.7+36.5 using mental math

The customer support department for a major computer supplier believes that the time between consecutive phone inquiries is exponentially distributed, with an average value of 60 seconds.

A baker made two cakes of the same size. -At the end of the day, there was 2/3 of a chocolate cake left. -There was 5/6 of a strawberry cake left.

A zookeeper predicted the weight of a new baby elephant to be 240 pounds when it was born. The elephant actually weighed 272 pounds at birth. What was the percent error of the zookeeper's prediction?

Before school, Janine spends 1/10 hour making her bed, 1/5 hour getting dress, and 1/2 hour eating breakfast. What fraction of an hour does she spend doing these activities?

There are 3 red and 8 green balls in a bag. If you randomly choose balls one at a time, with replacement, what is the probability of choosing 2 red balls and then 1 green ball? 4/165 24/605 1/10 72/1331

How much water should be added to 8 quarts of 90% antifreeze to get a 30% solution?

Work out the number that is halfway between 27 times 38 and 33 times 37

Math mystery: Case of the rouge runner clue 3

If the first step in the equation 2x-8=5x+3 is "subtract 2x," then in the form of a paragraph explain in complete sentences the next steps necessary to completely solve the equation for x.

A coffee shop surveyed three groups of 5 customers to find out how many cups of coffee the customers drink in one day. The table shows the results of the three samples.