Hands-on math!

Washington State Math Olympiad
Hints and Solutions
2015 Grade 5 Probability & Statistics
Problem

1) Your parents give you $1.25 for doing one chore and they double that amount for every additional chore. If you earn $8.75, how many chores did you do?

2) What is the probability of rolling a sum of 9 with 2 six-sided dice?
(Express your answer as a fraction in lowest terms )

3) There are 10 green marbles and 2 blue marbles in a bag. Each day you select a blue marble you can stay up an extra half hour. Each time you select a green marble you have to go to bed at 9 pm. You select a marble without looking and then put it back. Over the course of 12 days how many days would you expect to go to bed after 9pm?

Problem

4) Riona has a clothes drawer containing socks. She has 13 white socks, 12 red socks, 7 blue socks, and 4 green socks. If she takes one sock out at random, what is the probability of drawing a red sock?
(Express your answer as a fraction in lowest terms )

5) Given the blanks in the following list of whole numbers, such that the mean and median will be 17 and there will only be one mode . What is the mode?

      3, __, 11, __, 16, __, 20, 23, 28, 32