Multiplying fractions word problem: pigging out on pumpkin pie | Pre-Algebra | Khan Academy

TL;DR

Ken and Isaiah are trying to figure out how much pumpkin pie they have eaten, but Ken mistakenly multiplies 2/5 by 7 instead of adding 2/5 seven times.

Transcript

Ken and Isaiah are eating pumpkin pie with their friends. They want to figure out how much pie they have eaten so far. There are 7 of them in total and each of them has eaten 2/5 of a pie. Ken said you can solve this problem by multiplying 2/5 times 7. And that makes sense. Each of them ate 2/5, and there are 7 folks. I would multiply 2/5 times 7. ... Read More

Key Insights

• 🥺 Ken mistakenly multiplied instead of adding, leading to an incorrect calculation.
• ✖️ Multiplying a fraction by a whole number does not change its value.
• ⌛ Adding 2/5 seven times is equivalent to multiplying 2/5 by 7.

Questions & Answers

Q: What mistake did Ken make in his calculation?

Ken mistakenly multiplied 2/5 by 7 instead of adding 2/5 seven times. This resulted in an incorrect answer.

Q: How should Ken have calculated the amount of pie eaten?

Ken should have added 2/5 seven times, as each person ate 2/5 of a pie. This would have given him the correct answer.

Q: Why is 14/35 less than one whole pie?

14/35 is less than one whole pie because it is equivalent to 2/5, which represents the amount of pie only one person should have eaten. It is not the total amount eaten by all seven people.

Q: How could Ken have simplified the calculation?

Ken could have simplified the calculation by multiplying 2/5 by 7/1, as 7/1 is equal to 7. This would have resulted in the same answer, 14/5 or 2 and 4/5.

Summary & Key Takeaways

• Ken and Isaiah are eating pumpkin pie with their friends and want to calculate how much pie they have eaten.

• Ken mistakenly multiplies 2/5 by 7 instead of adding 2/5 seven times.

• The correct answer is 14/5 or 2 and 4/5.