Math Counts

Mario and I try to encourage our children to get as much math as possible. We were excited when Eric came home and told us that he chose Math Counts as his elective this year in 7th grade. Now before you call him a nerd, let me say, the alternatives were things like chorus and band. So math didn't sound to bad compared to music classes. To get into Math Counts, you have to have a strong background in Math. Fortunately Eric was selected to be in the class. His teacher recently sent home a newsletter with some samples of math problems that they work on. I consider Mario and I pretty good at math, but some of these problems made us say "What in the World?!" You can test your math skills with some of these sample problems:

The average age of a group of teachers and students is 20. The average age of teachers is 35. The average age of students is 15. What is the ratio of teachers to students? Express your answer as a fraction in simplest form.

Find the smallest positive whole number that does not contain the digit 9, but it is divisible by 999.

George has a combination lock with the numbers 0 -39. He must enter three numbers in the correct order to open the lock. He tells his friend Jordy that one of the numbers is 23. What is the probability that Jordy guesses George's combination correctly?

It gives me a headache just trying to figure out how to start figuring these problems out. Today we took Eric to Subway for lunch. We told him it was a working lunch and he needed to show us how to solve that first problem (on his napkin.) Mario and I thought that the problem was definitely missing some important information. But Eric quickly showed us how to solve the problem.