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Problems of the Week – December 31 to January 4

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: Ella plants a dozen seeds. Half of those seeds sprout and grow into plants. Each of those plants grows 3 flowers. How many flowers does Ella have?
Answer: 18 flowers
Solution: A dozen means 12. So, since half of Ella’s 12 planted seeds sprout, that means 6 seeds sprout and grow into plants. Each of those plants grows 3 flowers, so Ella has 3 + 3 + 3 + 3 + 3 + 3 = 18 flowers.

[6]Upper Elementary:
Question: A truck that weighs 4 tons when empty carries 1 ton of gravel. The driver unloads 500 pounds of gravel at a construction site. How many pounds do the truck and the gravel weigh in total now?
Answer: 9,500 pounds
Solution: A ton is 2,000 pounds, so the truck itself weighs 2,000 × 4 = 8,000 pounds. The truck starts with 2,000 pounds of gravel, so after it leaves the construction site, it has 2,000 – 500 = 1,500 pounds of gravel in the back. In total, that’s 8,000 + 1,500 = 9,500 pounds.

[7]Middle School:
Question: Mason scores 40 points on his fifth of five quizzes, increasing his average score to 32 points. What was Mason’s average score after the first four quizzes?
Answer: 30 points
Solution: If Mason’s average point score over 5 tests was 32 points, then he must have earned 32 × 5 = 160 points in total. Before his last test, he had 160 – 40 = 120 points over 4 tests. So, his average score after 4 tests was 120 ÷ 4 = 30 points.

[8]Algebra and Up:
Question: Puppies sleep an average of 12 hours each day. Kittens sleep an average of 20 hours each day. If a puppy is 4 weeks older than a newborn kitten, then how old will the kitten be when the kitten and the puppy have gotten the same amount of sleep in total?
Answer: 42 days
Solution: There are 28 days in 4 weeks, so the puppy has gotten 12 × 28 = 336 hours of sleep by the time the kitten is born. We want to know when the amount of sleep is equal. The kitten sleeps at a rate of 20 hours per day, and the puppy sleeps 12 per day with a 336-hour lead. We can set up the following equation and solve for d days:

20d = 12d + 336
d = 42

The kitten will be 42 days old.