What is the fastest way to solve this?

[M7MBA]

What is the fastest way to solve this?

\(\dfrac{(0.513)(0.488)(0.942)}{(0.684)(0.314)(0.183)}\)

a) 4
b) 5
c) 6
d) 7
e) 8

Answer: C

Source: GMAT Paper Tests

[regor60]

Try rounding.

First term down to 1/2. Second term up to 1/2, third term up to 1. Adjusted numerator of 1/4.

Adjust first term in denominator down to 2/3, second term up to 1/3, third term up to 1/5. Revised denominator of 2/45.

Notice that this revises terms up and down an equal number of times between numerator and denominator which helps offset estimation errors.

New fraction of (1/4)/(2/45) =45/8. 45/8 is closer to 48/8 than it is to 40/8.

48/8 =6,C