Hands-on math!

Washington State Math Olympiad
Hints and Solutions
2012 Grade 8 Probability and Statistics
Problem
1) Billy and Bobbi are playing a dice game. Billy rolls a six sided die four times and adds the face values together. Bobbi rolls a 12 sided die twice and adds the face values together. What are the odds of Billy rolling a 23 compared to Bobbi rolling a 23?

2) Jordi's math class of 20 students took a quiz. The average score was 80 points out of 100 points. The range of the quiz scores separating the low score from the high score was 25 points. Jordi wonders what the lowest score could be. What is the lowest possible score?

3) There are ten jelly beans in a sack. Four are mint flavored, three are celery flavored, two are licorice flavored, and the last is peanut butter flavored. Nyang, who doesn't like peanuts, but loves celery, reaches in and grabs two jelly beans and eats them without looking. What is the probability that one was celery flavored, and the other was not peanut flavored?

Problem
4) Many Flavors Gelato Bar has 7 flavors of gelato today, 2 kinds of gooey sundae sauces, and a choice of chocolate sprinkles or chopped nuts topping. Across the street Mama's Ice Cream Parlor has 6 flavors of ice cream, 3 kinds of gooey sundae sauces, and a choice of two kinds of sprinkles for topping, chocolate or fruity. Selena likes having lots of choices. If she is going to make a sundae out of 2 scoops of gelato or ice cream, one sundae sauce and one topping, which store will give her more options and how many more? She can choose to have both scoops be the same flavor.

5) Sweet Raisins sells 1.5oz boxes of raisins. Not all the boxes have the same number of raisins. In a quality control check 25 boxes were randomly selected and checked for weight and number of raisins. The graph displays the data for the number of raisins. Compare the distance between the furthest point out and the mean to the mean. Express your answer as a percent to the nearest whole number.