Hands-on math!

Washington State Math Olympiad
Hints and Solutions
2014 Grade 7 Number Sense

Problem

1) Grandpa tells Nelli he has an investment in a fund that has a history of increasing in values by 6.2% every year. He has $32,000 invested in that fund. He asks her to compute how much the fund will earn him over five years if he makes no changes to his investment. Express your answer to the nearest cent.

2) Ben wants to make a lot of crepes. He has 3 cups of milk left and 1 and 1/2 cup of flour. He has plenty of eggs and everything else he needs. The recipe calls for 3/4 cups milk and 3/8 cup flour and yields 6 crepes. What is the maximum number of crepes he can make with the ingredients he has?

3) The numbers 1 - 32 can be represented with a set of five lights using the binary system. An on light is recorded with a 1, an off light is recorded with a 0. With the pattern given in the table, how would the number 23 be represented in 1's and 0's?

Problem

4) The volleyball coach recorded the ratios of successful serves for the four best players as shown in the table. Based on the current records, if they were all to serve 20 times, what would be the difference in number of successes between the top record and the second best record? Round to whole number of serves.

5) a) Which expression is bigger:
    (-1/2) + (1/3) + (-1/4) or
    (-1/2)(1/3)(-1/4)?
b) How much bigger is it?
Express your answer as a reduced fraction.