Math Problem Monday - September 10th, 2018 | Mathnasium Livermore, CA

Sep 10, 2018 | Livermore

Lower Elementary
Question: John earns $7 an hour at his job. At the end of the week he earned $84 dollars. His sister thinks he worked 10 hours that week. Is John’s sister right? Explain your answer.
Answer: No, if John worked 10 hours he would have made $70. John worked 12 hours.

Upper Elementary
Question: A certain snail can crawl 7 inches in 1 minute.  How far can it crawl in 4 1/2 minutes?
Answer: 31 1/2 inches.

Middle School
Question: If 18 is 30% of a number, what is 75% of the same number?
Answer: 45
Note there are several ways to solve this problem. First, find out the answer to “18 is 30% of what number?”, then find 75% of that number. To solve algebraically, either a percent equation can be formed: .30n = 18 and then solve for n = 60 or use a proportion 18/n = 30/100 and solve for n = 60.  To solve in a number sense way:  if 30% of a number is 18, then to find 10% of the number divide 18 by 3. That gives 6.  Then to find 100% multiply 6 by 10 = 60. Then to find 75% of 60 find 3/4 of 60 = 45.

Algebra and Up
Question: A larger cube is formed by taking the length of each edge of a smaller cube and multiplying by 4.  How much greater is the volume of the larger cube than that of the smaller cube?
Answer: 64 times as great.
Note: An algebraic solution would be let the length of an edge of the smaller cube = n. Then the volume of the small cube is n x n x n = n3.  That means the length of an edge of the larger cube is 4n.  It’s volume is 4n x 4n x 4n = 64n3. We can see it is 64 times as great as the smaller cube’s volume.
An arithmetic solution would be to let the length of an edge of the smaller cube = 1.  Then the volume of the small cube is 1 x 1 x 1 = 1. The length of an edge of the larger cube would be 4.  It’s volume is 4 x 4 x 4 = 64.

Math tutors near

Could not find Center, try again