Hands-on math!

Washington State Math Olympiad
Hints and Solutions
2015 Grade 8 Probability and Statistics
Problem
1) A basketball player attempted 1789 free throws. He made 801 of them. What is the probability that the player will make the next shot he attempts? Write the probability as a decimal rounded to the nearest thousandth.
2) Elite Style inspects 500 hair dryers manufactured and finds 495 to have no defects. There are 20,000 hair dryers in their warehouse. Predict the number of hair dryers in the warehouse that will have no defects.

3) A data set consists of seven different positive whole numbers. The mean of the data is 76. What is the largest possible median of the data?

Problem
4) Hannah has a bag of marbles. 13 are yellow, 16 are green, 23 are red, 8 are blue, and 6 are multicolored. The multicolored marbles are red and blue. If Hannah randomly selects a marble, what is the probability that the marble will have red or blue in it? Express your answer as a ratio.

5) The histogram shows the number of hours students in Mrs. Bell's business class average at their part-time jobs. What is the probability that a student randomly selected from the business class works 5-10 hours per week?