Click here [1] for the Problem Extension Worksheet version of the Problems of the Week.
Click here [2] for an MS Word version of the Problems of the Week.
Click here [3] for the Canadian Problem Extension Worksheet version of the Problems of the Week.
Click here [4] for a Canadian MS Word version of the Problems of the Week.
[5]Lower Elementary:
Question: Willy bought a candy bar for 99¢ and a bottle of water for $1.26. If he pays with a $5 bill, what is Willy’s change?
Answer: $2.75
Solution: The total amount Willy spent is 99¢ + $1.26 = $2.25. Because he pays $5, he will receive $5.00 – $2.25 = $2.75 as change.
[6]Upper Elementary:
Question: Tiffany arrived at the airport at 3:50 PM. Her flight was supposed to leave at 5:15 PM, but it was delayed for 2 hours. How long was Tiffany at the airport before her flight left?
Answer: 3 hours and 25 minutes
Solution: The plane left 2 hours after 5:15 PM, which means it left at 7:15 PM. It is 25 minutes from 3:50 PM to 4:15 PM and then it is 3 hours from 4:15 PM to 7:15 PM, so the total time Tiffany was at the airport was 3 hours and 25 minutes.
[7]Middle School:
Question: There are three candidates for class president. Becky received 25% of the total votes. Charles received 45% of the votes. Daniella received 300 votes. What is the total number of votes in the election?
Answer: 1,000 votes
Solution: We need to find the percent of the votes that Daniella received. From 100% of the votes, Becky has 25% of the votes and Charles has 45% of the votes. So Daniella has 100% – 25% – 45% = 30% of the votes. Since 300 votes represent 30% of the total votes, that means that 100 votes represent 10% of the total votes. So 1,000 votes represent 100% of the total votes.
[8]Algebra and Up:
Question: Gerald can paint a fence in 2 hours. Mandy can paint a fence in 3 hours. How long will it take them to paint a fence together?
Answer: 1 hour and 12 minutes
Solution: Gerald can paint 1 fence in 2 hours, so his rate is 1/2. Mandy can paint 1 fence in 3 hours, so her rate is 1/3. If we let x be the rate at which they can paint a fence together, they can paint 1 fence in x hours, so the rate is 1/x. So our equation is:
1/2 + 1/3 = 1/x
Combine the fractions.
5/6 = 1/x
Find the cross product.
5x = 6
Divide by 5.
x = 6/5 = 1 1/5
Together, Gerald and Mandy can paint a fence in 1 and 1/5 hours, or 1 hour and 12 minutes.