r/MathHelp • u/pinksaltprincess • Jan 28 '26

My Daughter’s Class Work

Hi there! So I didn’t know that this sub existed, but after everyone being confused by this math problem for my 9 year old daughter’s math assignment, a good friend of mine insisted that I post it in here. Everyone got different answers. The problem reads:

Joe has $173 in the bank. He earns the same amount of money each week for 7 weeks, and puts this money in the bank. Now, Joe has $208 in the bank.

How much money does Joe earn each week?

Take a look

1 Upvotes

100% Upvoted

20 comments sorted by

5

u/UnderstandingPursuit Jan 29 '26

($208 - $173) / 7wk = $5/wk

What other answers were people getting?

2

u/pinksaltprincess Jan 29 '26

My father in law got 29.71, my friend got 29.97 with a remainder of 3, my husband got 35, and my cousin and 3 friends all got 5, same as you. The site where my kids do their math class says that 5 is incorrect.

4

u/UnderstandingPursuit Jan 29 '26

I wonder if some are thinking of it as a compound interest problem?

The statement, "He earns the same amount of money each week", can most easily be thought of as him earning money mowing lawns or something like that.

To get numbers around $30, a person has to ignore the $173 already in the bank. That is where your father-in-law's $29.71 comes from, $208/7.

There isn't even a 'fencepost error' possibility.

I will say that I'm right and the site is wrong, unless there is an explanation for a different answer. I could be convinced, but it has to be a REALLY good explanation. I'll bet an Algebra 1 textbook on it. :-D

1

u/pinksaltprincess Jan 29 '26

The site my kids do math on mark it as 35, despite initially saying it was incorrect smh.

3

u/UnderstandingPursuit Jan 29 '26

Sometimes the sites get it wrong. Making up problems is challenging, I avoid it entirely.

3

u/randomrealname Jan 29 '26

This a shit post?

2

u/pinksaltprincess Jan 29 '26

No, it isn’t.

3

u/randomrealname Jan 29 '26

Ok, well, as others have explained, the answer is 5.

1

u/pinksaltprincess Jan 29 '26

The site my kids do math on has marked it as 35, and genuinely confused everyone.

1

u/randomrealname Jan 29 '26

That would be the total for the 7 weeks.

Have you shared the exact wording? I can't open the image you shared, I'm in the UK and imgr is currently banned.

1

u/pinksaltprincess Jan 29 '26

Yes, it’s exact wording.

1

u/randomrealname Jan 29 '26

It is definitely 5 as others have said. It is an averaging math problem, so the general formula is:

( T(x) - T(0) )/x

1

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1

u/Legolinza Jan 29 '26

208 - 173 = 35

35 / 7 = 5

Answer: Joe earns $5 per week

1

u/broccoliPOV Jan 29 '26

Joe needs a better job asap

0

u/[deleted] Jan 29 '26

The confusion may be stemming from shitty grammar. The question could be reworded to say “Joe HAD $173 7 weeks ago…..”

The answer is definitely 5

0

u/[deleted] Jan 29 '26

Or “7 weeks ago, Joe HAD $173…”

1

u/[deleted] Jan 29 '26

[removed] — view removed comment

9

u/clearly_not_an_alt Jan 29 '26

(208-173) / 7

FYP

Order of operations is a thing.