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 By: pearldyn (offline)  Sunday, April 04 2010 @ 09:39 PM CDT (Read 1667 times)
pearldyn

Can anybody teach me how to get the answer without drawing the fraction using blocks?

Question:
Arrange the four fraction below in order from the greatest to the smallest.

2/3 , 4/5 , 2/7 , 4/9

Thank you!

Junior

Registered: 06/17/09
Posts: 30

 By: belle (offline)  Sunday, April 04 2010 @ 11:17 PM CDT
belle

divide & convert to decimals.

2/3 = 0.667
4/5 = 0.8
2/7 = 0.285
4/9 = 0.444

so greatest to the smallest:

4/5, 2/3, 4/9, 2/7

Junior

Registered: 03/27/10
Posts: 19

 By: pearldyn (offline)  Tuesday, April 06 2010 @ 01:34 AM CDT
pearldyn

Ok, thats cool.......

But what happens when a P4 student who has not learn decimal to do that?

What other ways can you suggest?

Junior

Registered: 06/17/09
Posts: 30

 By: chocolateymuffin (offline)  Tuesday, April 06 2010 @ 02:14 PM CDT
chocolateymuffin

Hi,
for fractions to be comparable.....u have to make the denominators of the 4 fractions the same. Once the denominator is the same, u can then determine which is bigger/smaller by comparing the numerator. That's the usual approach.

In this case, the common denominator will be very large.....315? (correct me if I am wrong )

ALTERNATIVELY, notice that 2/3 and 2/7 both have 2 as the numerator while, 4/5 and 4/9 have 4 as the numerator. With some analysis, u dont have to convert them all into fractions with huge denominators. for example....if u compare, 2/3 and 2/7, 2/3 is greater than 2/7. While 4/5 is greater than 4/9.

So u have:

Great --------------------- Small

> 2/3 2/7
> 4/5 4/9

Then analyse where to put 4/5. Just by looking at the fraction, 4/5 is definitely larger than 2/7. but not so sure if it is bigger or smaller than 2/3? Convert both denominators to 15 and u will see that 4/5 is greater than 2/3. Place 4/5 infront of 2/3.

Great -----------------------Small
>4/5 , 2/3 , 2/7

Now analyse 4/9. Just by looking at the fractions, 4/9 is definitely smaller than 2/3 but not so sure if it is bigger or smaller than 2/7?
Convert both denominators to 63 and u will see that 4/9 is larger than 2/7.

Therefore, the fractions should be arranged as follows:

Greatest ----------------- Smallest
4/5, 2/3, 4/9, 2/7

HOPE THIS HELPS!!

I'm a mom of a P4 kid. Are u too? Good luck!

Newbie

Registered: 04/06/10
Posts: 1

 By: pearldyn (offline)  Tuesday, April 06 2010 @ 10:07 PM CDT
pearldyn

Thank you very much and it does really help!

Yes, chocolateymuffin, my son is in P4 and I am having trouble teaching him.
Its because I am not so good at math esp Fraction and next time will be Algebra.

Thank you for making me understand "the several ways of looking into it" which I have yet to practice.

Junior

Registered: 06/17/09
Posts: 30

 By: belle (offline)  Wednesday, April 07 2010 @ 02:09 AM CDT
belle

hi chocmuffin, great analysis. how did you get the common denominator of 315?

Junior

Registered: 03/27/10
Posts: 19

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