Hands-on math!

Washington State Math Olympiad
Hints and Solutions
2016 Grade 8 Probability and Statistics
Problem
Hint
1) A caterer is sorting silverware. There are 75 knives, 50 forks, and 75 spoons. Twenty of the forks and 30 of the spoons have red handles. If a piece of silverware is chosen at random, what is the probability that it will be a fork or have a red handle? Express as a simplified fraction. The probability of A or B is the probability of A + the probability of B.
2) A poll is taken and each person is asked two questions. The results are shown in the table. What is the probability that someone answered, "yes" to both questions? Express as a simplified fraction.
Find the 2 probabilities and multiply them together.

3) An estimate of the number of tagged foxes to the total number of foxes in a forest is 3:13. A forest warden recorded 21 tagged foxes. About how many foxes are in the forest if this observation is low by about 5%? Round to the closest whole number. (Partial fox should not be included.)
  1. If 21 tagged foxes are 5% below the expected tagged foxes, then the expected tagged foxes are ____ % of the tagged foxes which is _____ foxes.
  2. Set up the 3:13 ratio equated to this number of foxes divided by the estimate d number of foxes in the forest (call the total population X) and solve for X:




    Total foxes in the forest = _____

Problem
Hint
4) If a baseball player has 18 hits in 50 at bats, what is the probability that he will get a hit in his next at bat? Express your answer as a percent. Divide his hits by the at bats for the probability.

5) The circle graph below shows Art's Online total yearly sales by quarter. The total amount of sales for the year was $20 million. Find the sales for the 2nd quarter:
Turn the second quarter sales into a decimal and multiply by the total sales.