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Sub 505 (Easy)|   Arithmetic|   Roots|                     
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Which of the following is closest to (4.2(1,590)/15.7)^(1/2) ? 25 Jun 2018, 05:59
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90% (00:59) correct 10% (01:30) wrong based on 3454 sessions

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Which of the following is closest to \(\sqrt{\frac{4.2(1,590)}{15.7}}\)?

A. 20
B. 40
C. 60
D. 80
E. 100


(PS10470)­
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A
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Which of the following is closest to (4.2(1,590)/15.7)^(1/2) ? 25 Jun 2018, 06:09
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Solution



To find:
• The value closest to the expression \(\sqrt{\frac{4.2(1,590)}{15.7}}\)

Approach and Working:
As we are trying to find out the closest value, we can approximate the given terms as follows:
    • 4.2 ~ 4
    • 1590 ~ 1600
    • 15.7 ~ 16

Therefore, we can rewrite the expression as \(\sqrt{\frac{4(1,600)}{16}}\) = \(\sqrt{4 * 100}\) = 20

Hence, the correct answer is option A.

Answer: A
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Which of the following is closest to (4.2(1,590)/15.7)^(1/2) ? 25 Jun 2018, 06:09
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Bunuel
Which of the following is closest to \(\sqrt{\frac{4.2(1,590)}{15.7}}\)?

A. 20

B. 40

C. 60

D. 80

E. 100
Show more

ALWAYS check the answer choices before solving the question!
When we do so, we see that the answer choices are VERY spread apart, which means we can save a ton of time by being super aggressive with our approximations (aka rounding)

So, we get: \(\sqrt{\frac{4.2(1,590)}{15.7}} ≈ \sqrt{\frac{4(1,600)}{16}}\)

\(≈ \sqrt{4(100)}\)

\(≈ \sqrt{400}\)

\(≈ 20\)

Answer: A

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Which of the following is closest to (4.2(1,590)/15.7)^(1/2) ? 28 Jun 2018, 03:59
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Bunuel
Which of the following is closest to \(\sqrt{\frac{4.2(1,590)}{15.7}}\)?

A. 20

B. 40

C. 60

D. 80

E. 100



NEW question from GMAT® Official Guide 2019


(PS10470)
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4.2 ~ 4
1590~1600
15.7~16

\(\frac{4*1600}{16}\)
=\(\sqrt{(400)}\)
= 20

Thus the best answer is A.
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Which of the following is closest to (4.2(1,590)/15.7)^(1/2) ? 28 Jun 2018, 18:04
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Bunuel
Which of the following is closest to \(\sqrt{\frac{4.2(1,590)}{15.7}}\)?

A. 20

B. 40

C. 60

D. 80

E. 100
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First we can multiply the fraction by 10/10 and we have:

√[(42)(1,590)/157]

Approximating, we have:

√[(40)(1,600)/160]

√[(40)(10)] = √400 = 20

Answer: A
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Which of the following is closest to (4.2(1,590)/15.7)^(1/2) ? 25 Jun 2020, 06:41
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root of 4, 2
root of 1600, 40
root of 16, 4
2*40/4 is 20
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Which of the following is closest to (4.2(1,590)/15.7)^(1/2) ? 24 Dec 2020, 08:32
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Bunuel
Which of the following is closest to \(\sqrt{\frac{4.2(1,590)}{15.7}}\)?

A. 20

B. 40

C. 60

D. 80

E. 100

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\(\sqrt{\frac{4.2(1,590)}{15.7}}\)

=\(\sqrt{\frac{4*1,600}{16}}\)

\(=\sqrt{4*100}\)

\(=2*10\)

\(=20\)
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Which of the following is closest to (4.2(1,590)/15.7)^(1/2) ? 07 May 2021, 21:41
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Bunuel
Which of the following is closest to \(\sqrt{\frac{4.2(1,590)}{15.7}}\)?

A. 20

B. 40

C. 60

D. 80

E. 100
(PS10470)
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Answer: Option A

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