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Last Updated on May 11, 2023
GMAT OFFICIAL GUIDE PS
Solution:
Let’s estimate √3, √5, √6, and √7.
√3 ≈ 1.7
√5 ≈ 2.2
√6 ≈ 2.4
√7 ≈ 2.7
Thus:
A) 10 x 1.7 = 17
B) 9 x 2 = 18
C) 8 x 2.2 = 17.6
D) 7 x 2.4 = 16.8
E) 6 x 2.7 = 16.2
Alternate Solution:
Another way to get rid of the roots to compare each answer is to square each answer choice:
A) (10√3)^2 = 100 x 3 = 300
B) (9√4)^2 = 81 x 4 = 324
C) (8√5)^2 = 64 x 5 = 320
D) (7√6)^2 = 49 x 6 = 294
E) (6√7)^2 = 36 x 7 = 252
Answer: B
