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Re: Of the following, which is the best approximation to 0.0026^1/2 ? [#permalink]
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abhi758 wrote:
Of the following, which is the best approximation to \(\sqrt{0.0026}\)?
(A) 0.05
(B) 0.06
(C) 0.16
(D) 0.5
(E) 0.6

Kindly provide the steps to the solution. OA to be posted soon.


Backsolving 0.05^2 = .0025 it is nearest to .0026 hence A.
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Re: Of the following, which is the best approximation to 0.0026^1/2 ? [#permalink]
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When you have square or cubed roots of numbers that are less than 0 you can use the following.
For square roots:

Square root the number at the end of the decimal (so if it were (0.0026)^0.5, you would square root 26) and divide the number of decimal places by 2. In this case, we know that the square root of 26 is a tiny bit more than 5, and dividing the number of decimal places (4) by 2 gives you 2 decimal places. Thus the answer is approximately 0.05

Cube root of a number: same procedure as above, but we cube root the number at the end of the fraction and divide the number of decimal places by 3.
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Re: Of the following, which is the best approximation to 0.0026^1/2 ? [#permalink]
abhi758 wrote:
Of the following, which is the best approximation to \(\sqrt{0.0026}\)?
(A) 0.05
(B) 0.06
(C) 0.16
(D) 0.5
(E) 0.6

Kindly provide the steps to the solution. OA to be posted soon.



Square root of a number that has four digits to the right of decimal would have two digits to the right of decimals in the solution. So by this we rule out option D & E

Now the approx value of (26)^1/2 would be 5. The solution would therefore be A.

Hope this helps.
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Re: Of the following, which is the best approximation to 0.0026^1/2 ? [#permalink]
this is how I did it....
nearest to 26 is 25..root of this is 5
therefore, btw a) and d)
with 2 zeros before the decimal point, I took .05*.05 = 0.0025

so it is A...interesting one

HTH
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Re: Of the following, which is the best approximation to 0.0026^1/2 ? [#permalink]
I used scientific notation.

\sqrt{26*10^-4}

\sqrt{26}close to square root of 5 (25) ... 10^-4 becomes 10^-2 and ans is 0.05.

A.

Make sense?
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Re: sq root [#permalink]
Take the square of A, B, and C then take the 4th power of D and E. The closest is A or .0025.
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Re: sq root [#permalink]
= sqrt(26*10^-4)

= (10^-2)*sqrt(26)

ie approximately 0.05

Answer is A.
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Re: Of the following, which is the best approximation to 0.0026^1/2 ? [#permalink]
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Of the following, which is the best approximation to 0.0026^1/2 ? [#permalink]
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abhi758 wrote:
Of the following, which is the best approximation to \(\sqrt{0.0026}\)?

(A) 0.05
(B) 0.06
(C) 0.16
(D) 0.5
(E) 0.6


√0.0026 = √(26/10000)
= (√26)/(√10000)
≈ 5/100
≈ 0.05

Originally posted by BrentGMATPrepNow on 22 Aug 2016, 12:19.
Last edited by BrentGMATPrepNow on 21 Sep 2021, 17:55, edited 2 times in total.
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Re: Of the following, which is the best approximation to 0.0026^1/2 ? [#permalink]
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abhi758 wrote:
Of the following, which is the best approximation to \(\sqrt{0.0026}\)?

(A) 0.05
(B) 0.06
(C) 0.16
(D) 0.5
(E) 0.6


Since 0.05^2 = 0.0025 and 0.06^2 = 0.0036, we see that √0.0026 is between 0.05 and 0.06. However, since 0.0026 is closer to 0.0025 than it is to 0.0036, √0.0026 is closest to 0.05.

Answer: A
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Re: Of the following, which is the best approximation to 0.0026^1/2 ? [#permalink]
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