Marcus spent 10 hours doing his homework last week. This week he spent 11 hours doing homework. He says that he spent 110% more time doing homework this week. Is he correct? Show your work to justify your decision.
Giving medal to anyone who answers this. I know this is history but please help me with this.

Question

Marcus spent 10 hours doing his homework last week. This week he spent 11 hours doing homework. He says that he spent 110% more time doing homework this week. Is he correct? Show your work to justify your decision.
Giving medal to anyone who answers this. I know this is history but please help me with this.

e.mccormick · Answer

OK, so if you have something that is a percentage of something else, do you know how to set that up as a formula?

anonymous · Answer

This isn't correct. Technically speaking, you cannot go over 100% because it is the maximum of what you can go to.

e.mccormick · Answer

@FlameGod You do not understand percentages as completely as you think.  You can have more than 100%.  For example, if I sell something for 3 times as much as it costs,  have 200% profit.

e.mccormick · Answer

@ashley_13 Let me show an few examples.

5 is, 50% of 10.  So, what formulas can I make with that:

$10 \times 50\% = 5$

Now, 50% means the same as $\dfrac{50}{100}$ which becomes .5 as a decimal, so I could have written that as:
$10 \times \dfrac{50}{100} = 5$ or $10 \times .5 = 5$

OK, but what if I am missing one of them?

$10 \times 50\% = ?$

Simplest case, I just multiply.

$10 \times ?\% = 5$
$? \times 50\% = 5$

Those would need some more work.  A little algebra to move things where they need to be to find the unknown.

anonymous · Answer

@e.mccormick i dont fully understand?

e.mccormick · Answer

Well, they are asking you to confirm if this statment is true or not.  So, you need to test it mathematically.

anonymous · Answer

all i got is        10x110%=11  so do i put like 110 over 100 or something? @e.mccormick

e.mccormick · Answer

Whichever way you want.  There are three things.  Remove one then solve the other two to see if you get the same thing.

Also, I just noticed you posted this in History...  Should have aske it in the math area.  =)

anonymous · Answer

i realize tht but i culdnt figure out how to get to the math

e.mccormick · Answer

If you solve any of these:

$10\times 110\%=?$
$10\times ?\%=11$
$?\times 110\%=11$

And you get the original, it is true.

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anonymous · Answer

true i tink

anonymous · Answer

@e.mccormick i multiplied 10 by 110% and got ll so it it true?

e.mccormick · Answer

Yep.

anonymous · Answer

ok so the answer is yes he is correct because i multiplied 10 by 110% and got 11 ? @e.mccormick

e.mccormick · Answer

Yes, and the math you did is the justification.

anonymous · Answer

ok thank you so much you helped me  a whole lot! :) @e.mccormick

e.mccormick · Answer

np.  It is better to know how it works from an eample, then you can solve it... which you did.