Suppose that we flip a fair coin until either it comes up tails twice or it is flipped it six times. What is the expected number of times we flip the coin

The sum of the product of 4 and x and the product of 7 and y is 61. the sum of the product of 12 and x and the product of 21 and y is 61. what are the values of x and y?

An an average person has 6×10 by the power of two as many red blood cells as white blood cells a small sample of the blood has 7×10 by the power of three white blood cells about how many red blood cells are in the sample

Gabrielle's age is two times mikhail's age. the sum of their ages is 84. what is mikhail's age?