boomgoesthegmat wrote:1/3 + 1/2 - 5/6 + 1/5 + 1/4 - 9/20 =
A) 0
B) 2/15
C) 2/5
D) 9/20
E) 5/6
Answer: A
One option is to rewrite each fraction with the same denominator (a bit of work).
Another option is to convert each fraction to a decimal.
To do so, we need to know some BASE CONVERSIONS.
Let's use this chart
For example, if we know that 1/7 ≈ 0.14, then 2/7 ≈ 0.28
Likewise, if 1/6 ≈ 0.17, then 5/6 ≈ 0.83
[since 5/6 = 1 - 1/6 ≈ 1 - 0.17 ≈ 0.83]
So....
1/3 + 1/2 - 5/6 + 1/5 + 1/4 - 9/20 =
0.33 + 0.5 - 0.83 +
0.2 + 0.25 - 0.45
=
0 +
0
= 0
=
A
For more on converting fractions to decimals see this video:
https://www.gmatprepnow.com/module/gmat ... video/1066
Cheers,
Brent
