Lower Elementary
Question: Susan’s mother is 38 years old and Susan is 9 years old. How old will Susan be when her mother is 45 years old?
Answer: 16 years old
Upper Elementary
Question: What is 50% of 50%?
Answer: 1/4 or 25%
Middle School
Question: A bag contains 5 red marbles, 7 blue marbles, and 9 green marbles. Without looking in the back, what is the probability of pulling out a red marble and then reaching in and pulling gout another red marble?
Answer: 1/21 ≈ 0.478 = 47.8%
Note: The probability of reaching in and pulling out a red marble the first time is 5/21. Once that red marble has been removed the probability of pulling out another red marble is 4/20 (1/5). The probability of pulling out another red marble after initially pulling out a red marble is a dependent event so the probability is the product of 5/21 and 1/5 = 1/21.
Algebra and Up
Question: A triangle has the following side lengths, 17 cm and 12 cm. The measurement of the 3rd side must be less than what length?
Answer: 29 cm
Note: Assume that the area of the triangle is greater than 0. For this type of triangle, the length of a given side must be less than the sum of the other two sides. If the length is equal to the sum of the two sides this is a degenerate triangle which is a “triangle” formed by 3 collinear points and the area of the triangle is equal to 0. If the side length is greater than the sum of the other two sides the figure will not be closed and won’t for a triangle.
