Math 6 H Periods 1, 6 & 7 (Tues & Wed.)

Comparing Fractions 6-4

When 2 fractions have equal denominators-- it is easy to tell which of the fractions are greater. Compare their numerators.

5/11 < 7/11 because 5 < 7

If the fractions have different denominators, find a common denominator. Using the lCM of the denominators-- the LCD-- is a surefire way of determinng the relationship between fractions.
Which is greater 5/6 or 7/9?
Since the LCM (6,9) = 18
Using equivalent fractions
5/6 = 15/18
and 7/9 = 14/18
so 5/6 > 7/9

( See Section 6-2 notes if you need to review equivalent fractions)

Another way is to use cross products to compare.

What if you needed to name a fraction between two other fractions?

FOr instance, between 7/15 and 12/ 25

FInd the LCM (15, 25) using the methods taught from chapter 5
LCM ( 15, 25) = 75
finding equivalent fractions for
7/15 = 35/75
12/25 = 36/75
If you want a fraction between, simply double the denominators and then double the numerators
35/75 = 70/150
36/75 = 72/150
So 71/150 would be a fraction that is between the two given fractions.