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View Full Version : If 12 counters are 3/4 of a set, how many counters are there in a whole set?

jkwallace
Nov 28, 2011, 04:33 PM
How do I teach my daughter how to do this?

Unknown008
Nov 28, 2011, 09:25 PM
3/4 set -> 12 counters

Divide each side by 3/4, what do you get?

(3/4) / (3/4) = ?

Remember that a number divided by the same number gives 1.

12 \div $$\frac34$$ = 12 \times \frac43

Can you work this out? And the 1 set is a whole set, so you don't have anything more to do :)

jkwallace
Nov 29, 2011, 06:44 AM
Thank you! This is actually how I solved it, but I didn't know how to explain it to my daughter. At least we got through the homework... I guess it is now up to her teacher to explain the technique! Thanks again!

Unknown008
Nov 29, 2011, 07:22 AM
You can explain it using other values! For example:

If 20 apples makes 2 full crates, then 1 crate will have 10 apples. How did we come to this?

2 crates -> 20 apples
1 crate -> (20/2) = 10 apples

If now we were looking for how much do 3 crates hold instead of 1:

First we'd look for how much 1 crate hold, like the above, then multiply both sides by 3;

2 crates -> 20 apples
1 crate -> (20/2) = 10 apples
3 crates -> (10x3) = 30 apples

The same applies to fractions!

Half a crate has 5 apples. How many apples does 1 crate hold?

1/2 crate -> 5 apples
1 crate -> (5/ (1/2)) = (5*2) = 10 apples

jkwallace
Nov 29, 2011, 08:03 AM
Thank you, that does help. It is really about knowing when to multiply or divide the fractions... it is just hard for me (at 40) to wrap my head around which function best serves to answer the problem! Thank you very much, though, I will remember this when we study for the unit test! Have a great day!

Unknown008
Nov 29, 2011, 08:07 AM
Okay, if you need anymore help, don't hesitate :)

And you're welcome! ^_^