$$\sqrt{4.8\cdot10^9}$$ is closest in value to
(A) 2,200
(B) 70,000
(C) 220,000
(D) 7,000,000
(E) 22,000,000
The OA is B.
How can I compute this value? Experts, I ask for your help.
is closest in value to
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- Jay@ManhattanReview
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$$\sqrt{4.8\cdot10^9} = \sqrt{48\cdot10^8} = ~7\sqrt{10^8} = 7\cdot10^4 = 70,000$$Vincen wrote:$$\sqrt{4.8\cdot10^9}$$ is closest in value to
(A) 2,200
(B) 70,000
(C) 220,000
(D) 7,000,000
(E) 22,000,000
The OA is B.
How can I compute this value? Experts, I ask for your help.
The correct answer: B
Hope this helps!
-Jay
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- EconomistGMATTutor
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Hi Vincen,$$\sqrt{4.8\cdot10^9}$$ is closest in value to
(A) 2,200
(B) 70,000
(C) 220,000
(D) 7,000,000
(E) 22,000,000
The OA is B.
How can I compute this value? Experts, I ask for your help.
Let's take a look at your question.
We are asked to find the the closest value of $$\sqrt{4.8\cdot10^9}$$.
Let's write 10^9 as 10 x 10^8.
$$\sqrt{4.8\times10\times10^8}$$
$$=\sqrt{48\times10^8}$$
$$\approx\sqrt{49\times10^8}$$
$$\approx7\times10^4$$
$$\approx70,000$$
Therefore, Option B is correct.
Hope this helps.
I am available if you'd like any follow up.
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- Brent@GMATPrepNow
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ASIDE: the above solutions take advantage of a very useful rule that says...
√(xy) = (√x) (√y)
This will save you time finding the square roots of big products.
For example, to evaluate √(81 x 64), we COULD find the product of 81 and 64 to get 5184
But this means we have to find √5184, which is awful!!
However, if we apply the above rule, we get: √(81 x 64) = (√81)(√64) = (9)(8) = 72
Cheers,
Brent
√(xy) = (√x) (√y)
This will save you time finding the square roots of big products.
For example, to evaluate √(81 x 64), we COULD find the product of 81 and 64 to get 5184
But this means we have to find √5184, which is awful!!
However, if we apply the above rule, we get: √(81 x 64) = (√81)(√64) = (9)(8) = 72
Cheers,
Brent
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- Scott@TargetTestPrep
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We can rewrite the expression as:Vincen wrote:$$\sqrt{4.8\cdot10^9}$$ is closest in value to
(A) 2,200
(B) 70,000
(C) 220,000
(D) 7,000,000
(E) 22,000,000
The OA is B.
How can I compute this value? Experts, I ask for your help.
√(48 x 10^8)
which is approximately:
√49 x √10^8
7 x 10^4 = 70,000
Answer: B
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