Lower Elementary
Question: Mr. Demming’s class is having a pizza party. If one pizza feeds 3 children, how man pizzas will Mr. Demming’s need to order to feed 27 children?
Answer: 9 pizzas
Solution: Since each pizza feed 3 children, we find how many pizzas Mr. Demming needs to buy by finding how many times 3 are there in 27. Because 3 ten times is 30, one less 3, or nine 3s, equals 27. So Mr. Demming would need to buy 9 pizzas.
Upper Elementary
Question: The first official Memorial Day was Celebrated in May 1868. How many Memorial Days will the United States celebrated 5 years from this Memorial Day?
Answer: 150
Solution: To solve this problem we first need to find how far it is from 1868 to 2012. This is done by using subtraction.
2012 – 1868 = 144 years
Because Memorial Day was celebrated in 1868, we need to include that year, so from 1868 to 2012, the United States has celebrated 145 Memorial Days (144 + 1).
In 5 years the United States will have celebrated 150 Memorial Days (145 + 5).
This problem can also be solved mentally by first finding how far 1868 is to 1900 (32 years), then from 1900 to 2000 (100 years), then from 2000 to 2017 (17 years), and finally the inclusive year (1 year).
32 + 100 + 17 + 1 = 150 years
Middle School
Question: If two elephants can eat 200 peanuts in two minutes, how many elephants will it take to eat 1800 peanuts in six minutes?
Answer: 6 elephants
Solution: A common mistake students make is to assume that if two elephants eat 200 peanuts in two minutes, that one elephant eats 100 peanuts per minute. This is not the case. Since it takes two elephants to eat 200 peanuts in two minutes, it takes one elephant two minutes to eat 100 peanuts. So in six minutes one elephant can eat 300 peanuts. That means it will take 6 elephants to eat 1800 peanuts in six minutes.
Algebra and Up
Question: A sports car traveling at 97 miles per hour passes a van traveling 53 miles per hour. After 10 seconds how many feet ahead of the van is the sports car? (Round final answer to the nearest tenth of a foot)
Answer: 645.4 feet
Solution: Since the problem is asking for the number of feet ahead after 10 seconds, it would be a good idea to start by converting the sports car and the van’s speed to feet per second.
Sports Car:
97(miles/hour) â— 5280 (feet/mile) â— 1/60 (hours/min) â— 1/60 (min/sec) ≈ 142.27 ft/s
Van:
53(miles/hour) â— 5280 (feet/mile) â— 1/60 (hours/min) â— 1/60 (min/sec) ≈ 77.73 ft/s
After 10 seconds the sports car has traveled 1422.7 feet and the van has traveled 777.3 feet. Finding the difference between the distances traveled will give us how far ahead the sports car is.
1422.7 – 777.3 = 645.4 feet
