Hands-on math!

Washington State Math Olympiad
Hints and Solutions
2015 Grade 7 Probability and Statistics
Problem

1) Jen's warehouse receives a shipment of 700 refurbished toasters. She tests 40 of them at random for defects and finds 2 with power supply failure. If this sample is representative of the entire shipment, how many toasters should Jen expect to have power source failure?

2) A set of five 2-digit whole numbers has a mean of 16, a mode of 13, and a median greater than the mean. What is the largest possible value of the largest number of the set?

3) You have a bag containing 5 red candies, 7 blue candies, 8 green candies, and 12 yellow candies. If you pull candies from the bag at random, what is the minimum number you would have to take to ensure getting 3 of at least one color?

Problem

4) A six-sided die is weighted so it rolls 6 five times as often as any other number. If it rolls 6 five times in a row, what is the probability it will roll 6 on the sixth roll?

5) There are 5 little league baseball teams in your county. There are 4 teams in a neighboring county. Each team will play three games against each of the other teams within their county and two games against each of the teams in the neighboring county. How many total games will be played by the end of the season?