Explanation Always scan the answer choices

BEFORE performing any calculations.

Since the answer choice are very spread apart, we can be very aggressive with our estimation.

We're going to use a nice rule that says

√(ab) = (√a)(√b)We have √(2.3 x 10⁹)

Since 2.3 isn't an easy number to find the square root of, the above

rule doesn't help us much.

However, what if we do the following:

√(2.3 x 10⁹) = √(2.3 x 10¹ x 10⁸)

= √(23 x 10⁸)

How does this help?

Well, 23 is pretty close to 25 and we know that √25 = 5.

Can we do this? You bet. Remember that since the answer choice are very spread apart, we can be very aggressive with our estimation

We get:

√(23 x 10⁸) = (√23)(√10⁸)

≈ 5(10⁴)

≈ 5(10,000)

≈ 50,000

Answer: A

Cheers,

Brent

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Brent Hanneson – Creator of greenlighttestprep.com

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