MHB Fraction Multiplication: How to Multiply Fractions and Mixed Numbers

[David39ni]

I am finding it hard to understand this questions its sounds more like fraction subtraction than multiple but the army test sample questions says its multipication

You have 3 1/4 boxes of paper. You give 1/2 to the paper to a colleague, how many boxes of paper do you have left.

The test says 1 5/8 i don't understand how they get to that. Now when i did prob did it wrong i got 22 / 12 I don't now how they get 1 5/8.

This is not home work this is revision questions available on the site to practise the type of quesitons I might be getting.

 

[MarkFL]

Hello and welcome to MHB, David39ni! (Wave)

If you give away 1/2, then you have 1/2 left. So all we need to do is find what one-half of what you began with is:

$$\frac{1}{2}\cdot3\tfrac{1}{4}=\frac{1}{2}\cdot\frac{3\cdot4+1}{4}=\frac{1}{2}\cdot\frac{13}{4}=\frac{13}{8}=\frac{8+5}{8}=1\tfrac{5}{8}$$

Does that make sense?

 

[David39ni]

Not really sorry wish this site had videos you still don't how their answer what i said ?

 

[MarkFL]

Not really sorry wish this site had videos you still don't how their answer what i said ?

I am assuming you understand that if you give half of something away, you are left with one-half yourself.

Another way to look at finding one half of the original amount is:

$$\frac{1}{2}\cdot3\tfrac{1}{4}=\frac{1}{2}\left(3+\frac{1}{4}\right)=1\tfrac{1}{2}+\frac{1}{8}=1\tfrac{4}{8}+\frac{1}{8}=1\tfrac{5}{8}$$

This is actually more in line with how I would picture it mentally. :D