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the best approximation of √ (3.8 × 10^25)

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by sanju09 » Tue Sep 14, 2010 5:41 am
Which of the following is the best approximation of √ (3.8 × 10^25)?
(A) 1.9 × 10^5
(B) 6.2 × 10^5
(C) 1.9 × 10^12
(D) 6.2 × 10^12
(E) 1.9 × 10^25


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Source: — Problem Solving |

by selango » Tue Sep 14, 2010 5:56 am
sqrt(38*10^24)

6.2*6.2=38.44

=6.2*10^12

Pick D
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by Scott@TargetTestPrep » Tue Jan 09, 2018 10:21 am
sanju09 wrote:Which of the following is the best approximation of √ (3.8 × 10^25)?
(A) 1.9 × 10^5
(B) 6.2 × 10^5
(C) 1.9 × 10^12
(D) 6.2 × 10^12
(E) 1.9 × 10^25
We want the exponent of the 10 to be an even number, because taking the square root is easier if the exponent is even. Let's simplify the given equation:

√(3.8 x 10^25) = √(38 x 10^24) = √38 x √10^24 = √38 x 10^12 ≈ 6.2 x 10^12

Answer: D

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