Question
A construction worker bought 21 7/8
Pounds of nails when those nails were all used she bought 2 1/2 times as many nails as she had bought the first time how many pounds of nails did she buy the second time
Pounds of nails when those nails were all used she bought 2 1/2 times as many nails as she had bought the first time how many pounds of nails did she buy the second time
Answers
Ms. Sue
Let's use equivalent decimals.
21.875 * 2.5 = _______ pounds
21.875 * 2.5 = _______ pounds
Damon
21 7/8 * 2 1/2
one way is to use distributive property
(21 + 7/8)(2 + 1/2)
=(2 + 1/2)(21) +(2 + 1/2)(7/8)
= 42 + 21/2 + 7/4 + 7/16
= 42 + 168/16 + 28/16 + 7/16
= 42 + 203/16
= 42 + 12 + 11/16
= 54 11/16
one way is to use distributive property
(21 + 7/8)(2 + 1/2)
=(2 + 1/2)(21) +(2 + 1/2)(7/8)
= 42 + 21/2 + 7/4 + 7/16
= 42 + 168/16 + 28/16 + 7/16
= 42 + 203/16
= 42 + 12 + 11/16
= 54 11/16
Jen
If your teacher wants to keep it in fractions...
Convert 21 7/8 into an improper faction of 175/8 and 2 1/2 into 5/2. Multiply together and reduce/ convert to mixed fraction of 54 11/16.
Convert 21 7/8 into an improper faction of 175/8 and 2 1/2 into 5/2. Multiply together and reduce/ convert to mixed fraction of 54 11/16.
Jenny
You get 54 11/16 but the thing I don't know is that if you multiple you get the answer and if you divide you get the answer
Jen
Since the problem says "2 1/2 times" you are going to multiply. If you are getting the same answer dividing, you are dividing incorrectly. My guess is that you are not flipping the second fraction before multiplying when you are dividing (to divide fractions, you flip the second fraction and multiply).
Ms. Sue
What are you multiplying? What is the answer?
What are you dividing? What is the answer?
What are you dividing? What is the answer?
Damon
multiplying by 5/2 should not give the same answer as multiplying by 2/5(which is dividing by 5/2)
Jenny
In the answer choices I get both of the answer if you multiple 21 7/8 and 2 1/2 you get 54 11/16 and if you divide 21 7/8 and 2 1/2 you get 8 3/4
Ms. Sue
Jenny -- which answer makes sense to you?
She bought more than twice as many nails the second time.
Did she buy over 54 pounds or almost 9 pounds the second time?
She bought more than twice as many nails the second time.
Did she buy over 54 pounds or almost 9 pounds the second time?
Jen
Many times, the author of an assignment will include common mistakes as answer choices. You then need to check your answer by making sure it makes sense. If she buys more than twice as much as she did the first time, will the answer be greater than or less than the amount she bought the first time?