How do you determine which fraction is greater 3/7 or 4/9?

2 Answers
Jan 13, 2016

Answer:

Divide one into the other. The resulting value will indicate which is the greater: #color(white)(....)4/9>3/7#

Explanation:

Consider #4/9-:3/7# giving:

#4/9xx7/3 =28/27# which is greater than 1 so

#4/9>3/7#

Sep 19, 2016

Answer:

#3/7 < 4/9#

Explanation:

A quick method is to cross multiply the fractions.

However, this only works if you multiply in the same direction every time. #color(red)("Red x Red")# first as shown below:

#color(red)(3)/color(blue)(7) and color(blue)(4)/color(red)(9)#

#color(red)(3xx9) and color(blue)(7xx4)#

#color(red)(27) < color(red)(28)#

#color(red)(3/7) < color(blue)(4/9)#

An alternative method is to get rid of the denominators

#xx LCD" "# which in this case is 63

#cancel63^9/1 xx3/cancel7 and cancel63^7/1xx4/cancel9#

#27 < 28#

#3/7 < 4/9#

Worst method - use a calculator!

Use a calculator to change them into decimals, then compare.

#3/7 = 0.42857...." "larr# smaller

#4/9 = 0.44444..." "larr# larger

You can also use a calculator to subtract the two fractions.
If you get a positive answer, then the first fraction was bigger.
If you get a negative answer then the first fraction was smaller.