Hands-on math!

Washington State Math Olympiad
Hints and Solutions
2006 Grade 5 Probability & Statistics
Problem
1) How many people must be present in a room in order to be 100% certain that two people in the room celebrate their birthdays in the same month?

2) The table shows the results of many spins that Jules made with a spinner. Based on these results, what is the probability that Jules's spinner will land on the apple on his next spin? Express your answer as a fraction in lowest terms.

3) Sidney took a survey of her fellow campers at summer camp and wants to show the results in a bar graph. She accidentally forgot to put the bar corresponding to redheads on the graph, but she correctly showed all other colors. If 50% of the campers have brown hair, 25 campers have brown hair, 5 campers have green hair, and 10 campers have black hair, how many of the campers have red hair? Fill in a bar for the redheads on the graph.

Problem
4) If 2 regular six-sided dice are tossed at the same time, what is the probability that the sum of the 2 dice will be less than or equal to 4?

5) You are the manager of the girls' basketball team. The championship game is coming up, and the coach has asked you to determine from his statistics which of his top three players has the best record for free throws. The statistical information you have is:
Joy made 21 out of her last 25 free throws.
Mary made 17 out of her last 20 free throws.
Nancy made 12 out of her last 15 free throws.
Tell the manager the order of his top 3 players: who is first, who is second, and who is third.