conflicting answers for fraction problem

mommykris

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Mar 18, 2007
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My daughter is in sixth grade and got a different answer than her teacher's answer book. She came up with -1 7/10. I just got -7/10. My husband got 0.1. Her teacher says the answer is 1. Here is the problem and my solution.

1/2 * -3 / 5/4 + 3/5 - 1/10 = ?

I did this:

1/2 * -9/3 = -9/6 or -3/2

-3/2 / 5/4 = -3/2 * 4/5 = -12/10 or -6/5

-6/5 = 3/5 = -3/5

-3/5 - 1/10 = -6/10 - 1/10 = -7/10

What do you say?
 
mommykris said:
1/2 * -3 / 5/4 + 3/5 - 1/10 = ?
What is the meaning of the second "slash" in "3/5/4"?

Also, grouping symbols would be very helpful. For instance, are the 1/2 and the 3 multiplied together? Or is the 1/2 multiplied on more?

Thank you.

Eliz.
 
The class is working on the order of operations (You know, "Please Excuse My Dear Aunt Sally"). There are no parentheses or exponents in the problem. It was presented like this:

1/2 * -3 divided by 5/4 + 3/5 - 1/10

I'm sorry that it wasn't clear. I hope this helps. Thanks.
 
mommykris said:
1/2 * -3 / 5/4 + 3/5 - 1/10 = ?
If that's the way "the teacher" wrote that down, he/she should be fired :shock:

-7/10 is correct IF this is intended:
(1/2) * -3 / (5/4) + 3/5 - 1/10 = ?
 
Sorry. Me again. To try to clarify some more, 1/2, 5/4, 3/5, and 1/10 are
all fractions.

That's all.
 
mommykris said:
There are no parentheses or exponents in the problem.
Perhaps as typed out on the sheet, using mathematical formatting. But as straight in-line text, grouping is almost certain required to convey what the sheet displays.

Do you mean any of the following...?

1/2 * -3 / 5/4 + 3/5 - 1/10

. . . . .[ (1/2)(-3) ] / (5/4) + (3/5) - (1/10)

. . . . .[ (1/2)(-3) ] / [(5/4) + (3/5)] - (1/10)

. . . . .[ (1/2)(-3) ] / [(5/4) + (3/5) - (1/10)]

. . . . .(1/2) [ (-3) / (5/4) ] + (3/5) - (1/10)

. . . . .(1/2) [ (-3) / (5/4) + (3/5) ] - (1/10)

There are other options, of course....

Eliz.
 
Sorry. Me again. To try to clarify some more, 1/2, 5/4, 3/5, and 1/10 are
all fractions.

Following the order of opp. You are correct.

-3(1/2) / (5/4) + (3/5) - (1/10)

(-3/2) / (5/4) + (3/5) - (1/10)

(-6/5) + (3/5) - (1/10)

(-3/5) - (1/10)

(-7/10)
 
Eliz.,

Based on the lesson as given, I suppose that the closest would be:

(1/2)(-3) / (5/4) + (3/5) - (1/10) =

As the lesson is about using the order of operations, any further or other grouping would defeat the purpose.
 
mommykris said:
Based on the lesson as given, I suppose that the closest would be:

(1/2)(-3) / (5/4) + (3/5) - (1/10)
Multiplication and division come before addition and subtraction, so:

. . . . .(1/2)(-3) = (1/2)(-3/1) = -3/2

. . . . .(-3/2) / (5/4) = (-3/2)(4/5) = -6/5

. . . . .-6/5 + 3/5 - 1/10 = -3/5 - 1/10 = -6/10 - 1/10 = -7/10

mommykris said:
As the lesson is about using the order of operations, any further or other grouping would defeat the purpose.
Not really. I've seen extremely complex fractional expressions assigned for "order of operations" homework. And such expressions would require extensive use of grouping symbols in a single-line format.

Eliz.
 
Thank you all very much. All your feedback has been very helpful. I'm glad I found you all.

:D
 
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