One person can do a certain job in fifteen minutes, and another person can do the same job in thirty minutes. how many minutes will it take them to do the job together?

In an experiment you are to flip a two sided coin 100 times and record 55 heads up and 45 tails up determine the theoretical and experimental probability of getting a heads up in the experiment.

The mean of a set of data is -3.82 and its standard deviation is 2.31. find the z score for a value of 3.99.

Aboard 60 in. long is cut two parts so that the longer piece is 5 times the shorter. what are the length of the two pieces?