Problems 0f the week 02-02-2021

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?

Upper Elementary:

Question: Tiffany arrived at the airport at 3:50PM. Her flight was supposed to leave at 5:15PM, but it was delayed for 2 hours. How long was Tiffany at the airport before her flight left?

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?

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?

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.

Upper Elementary:

Question: Tiffany arrived at the airport at 3:50PM. Her flight was supposed to leave at 5:15PM, 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 5:15PM, which means it left at 7:15PM. It is 25 minutes from 3:50PM to 4:15PM and then it is 3 hours from 4:15PM to 7:15PM, so the total time Tiffany was at the airport was 3 hours and 25 minutes.

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.

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 . Mandy can paint 1 fence in 3 hours, so her rate is . 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 . So our equation is:

  +  =

Combine the fractions.

 =

Find the cross product.

5x = 6

Divide by 5.

x =   = 1

Together, Gerald and Mandy can paint a fence in 1 and  hours, or 1 hour and 12 minutes.