What is the imaginary part of the following complex number -31?

What is the smallest integer n such that n\sqrt{2} is greater than 20

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.

Write an algebraic expression to match each statement a. four less than 8 times a number b. twice the difference of a number and six c. nine from a number squared