Author 
Message 
TAGS:

Hide Tags

Intern
Joined: 31 Aug 2014
Posts: 20

(4.8*10^9)^1/2 is closest in value to
[#permalink]
Show Tags
Updated on: 14 Sep 2015, 06:22
Question Stats:
78% (01:04) correct 22% (01:24) wrong based on 1437 sessions
HideShow timer Statistics
\(\sqrt{4.8*10^9}\) is closest in value to (A) 2,200 (B) 70,000 (C) 220,000 (D) 7,000,000 (E) 22,000,000
Official Answer and Stats are available only to registered users. Register/ Login.
Originally posted by ske on 14 Sep 2015, 06:07.
Last edited by Bunuel on 14 Sep 2015, 06:22, edited 1 time in total.
Renamed the topic and edited the question.




Math Expert
Joined: 02 Sep 2009
Posts: 64243

(4.8*10^9)^(1/2) is closest in value to
[#permalink]
Show Tags
18 Oct 2015, 12:30
\(\sqrt{4.8*10^9}\) is closest in value to(A) 2,200 (B) 70,000 (C) 220,000 (D) 7,000,000 (E) 22,000,000 \(\sqrt{4.8*10^9}=\sqrt{48*10^8}\approx {7*10^4}=70,000\). Answer: B.
_________________




Manager
Joined: 10 Aug 2015
Posts: 101

Re: (4.8*10^9)^1/2 is closest in value to
[#permalink]
Show Tags
14 Sep 2015, 06:29
ske wrote: \(\sqrt{4.8*10^9}\) is closest in value to
(A) 2,200 (B) 70,000 (C) 220,000 (D) 7,000,000 (E) 22,000,000 Solution: \(\sqrt{4.8*10^9}\) = \(\sqrt{48*10^8}\) = \(\sqrt{49*10^8}\) = \(7*10^4\) Option B




Manager
Joined: 13 Oct 2013
Posts: 130
Concentration: Strategy, Entrepreneurship

(4.8*10^9)^(1/2) is closest in value to
[#permalink]
Show Tags
18 Oct 2015, 13:28
(4.8*10^9)^1/2 =(48*10^8)^1/2 = (approx) (49*10^8)^1/2 =7*10^4 =70,000 Answer is B



GMAT Club Legend
Joined: 11 Sep 2015
Posts: 4879
Location: Canada

(4.8*10^9)^(1/2) is closest in value to
[#permalink]
Show Tags
18 Oct 2015, 13:35
Bunuel wrote: \(\sqrt{4.8*10^9}\) is closest in value to
(A) 2,200 (B) 70,000 (C) 220,000 (D) 7,000,000 (E) 22,000,000
Kudos for a correct solution. Eventually, we'll use a nice rule that says \(\sqrt{xy} = (\sqrt{x})(\sqrt{y})\)First rewrite \(\sqrt{4.8*10^9}\) \(\sqrt{4.8*10^9}\) = \(\sqrt{(4.8)(10^1)(10^8)}\) = \(\sqrt{(48)(10^8)}\) = (\(\sqrt{48}\))(\(\sqrt{10^8}\)) [applied rule from above]≈ (\(\sqrt{49}\))(\(\sqrt{10^8}\)) ≈ \((7)(10^4\)) ≈ \(70,00\)0 Answer: B ASIDE: we have a free video that covers various properties of roots  http://www.gmatprepnow.com/module/gmat ... video/1037
_________________
Test confidently with gmatprepnow.com



Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 10594
Location: United States (CA)

Re: (4.8*10^9)^(1/2) is closest in value to
[#permalink]
Show Tags
03 May 2016, 04:20
Bunuel wrote: \(\sqrt{4.8*10^9}\) is closest in value to
(A) 2,200 (B) 70,000 (C) 220,000 (D) 7,000,000 (E) 22,000,000
Kudos for a correct solution. We are given √(4.8 x 10^9), and we need to determine the answer choice that is closest in value. We first simplify the expression by eliminating the decimal point in 4.8. To do this, we can move the decimal one place to the right to get 48 and simultaneously reduce 10^9 to 10^8. So we need to estimate √(48 x 10^8). Notice that 48 is very close to 49, which is a perfect square. Note, too, that the square root of 10^8 is easy to calculate because the exponent is now an even number. So let’s evaluate √(49 x 10^8): √(49 x 10^8) √(49) x √(10^8) 7 x 10^4 70,000 Thus √(4.8 x 10^9) ≈ 70,000. Answer: B
_________________
5star rated online GMAT quant self study course See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews If you find one of my posts helpful, please take a moment to click on the "Kudos" button.



Intern
Joined: 04 Jun 2017
Posts: 6

Re: (4.8*10^9)^1/2 is closest in value to
[#permalink]
Show Tags
20 Sep 2017, 19:03
First method: Estimate
\(\sqrt{4.8 * 10^9}\) < \(\sqrt{10 * 10^9}\) \(\sqrt{4.8 * 10^9}\) < 100,000
\(\sqrt{4.8 * 10^9}\) is definitely less than 100,000 but close to 100,000 => answer is B
Second method: Calculation
\(\sqrt{4.8 * 10^9}\) = \(\sqrt{48 * 10^8}\) =
then take square roots of both parts: \(\sqrt{48}\) * \(\sqrt{10^8}\) = 4\(\sqrt{3}\) * 10^4 = 4 * \(\sqrt{3}\) * 10,000 = 40,000 * 1.7 (I memorized that \(\sqrt{3}\) is approximately 1.7) = ~68,000 => answer is B



VP
Joined: 09 Mar 2016
Posts: 1238

Re: (4.8*10^9)^(1/2) is closest in value to
[#permalink]
Show Tags
11 Nov 2017, 08:55
GMATPrepNow wrote: Bunuel wrote: \(\sqrt{4.8*10^9}\) is closest in value to
(A) 2,200 (B) 70,000 (C) 220,000 (D) 7,000,000 (E) 22,000,000
Kudos for a correct solution. Eventually, we'll use a nice rule that says \(\sqrt{xy} = (\sqrt{x})(\sqrt{y})\)First rewrite \(\sqrt{4.8*10^9}\) \(\sqrt{4.8*10^9}\) = \(\sqrt{(4.8)(10^1)(10^8)}\) = \(\sqrt{(48)(10^8)}\) = (\(\sqrt{48}\))(\(\sqrt{10^8}\)) [applied rule from above]≈ (\(\sqrt{49}\))(\(\sqrt{10^8}\)) ≈ \((7)(10^4\)) ≈ \(70,00\)0 Answer: B ASIDE: we have a free video that covers various properties of roots  http://www.gmatprepnow.com/module/gmat ... video/1037Hello, how did you get 10^4 from 10^8?



GMAT Club Legend
Joined: 11 Sep 2015
Posts: 4879
Location: Canada

Re: (4.8*10^9)^(1/2) is closest in value to
[#permalink]
Show Tags
11 Nov 2017, 09:03
dave13 wrote: Hello, how did you get 10^4 from 10^8? We want to find the square root of 10^8 So, what value when squared gives us 10^8? The answer is 10^4 (10^4)(10^4) = 10^8 In other words, (10^4)² = 10^8 So, the square root of 10^8 equals 10^4 Does that help? Cheers, Brent
_________________
Test confidently with gmatprepnow.com



Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 10594
Location: United States (CA)

Re: (4.8*10^9)^1/2 is closest in value to
[#permalink]
Show Tags
20 Dec 2017, 07:44
ske wrote: \(\sqrt{4.8*10^9}\) is closest in value to
(A) 2,200 (B) 70,000 (C) 220,000 (D) 7,000,000 (E) 22,000,000 √(4.8 x 10^9) is equivalent to √(48 x 10^8), which equals: √48 x √10^8 = 4√3 x 10^4 = 4 x 1.7 x 10,000 = 68,000 or about 70,000. Alternative solution: √(4.8 x 10^9) is equivalent to √(48 x 10^8), which is about √(49 x 10^8). We choose the number 49 because 49 is a perfect square. Now let’s simplify √(49 x 10^8): √49 x √10^8 = 7 x 10^4 = 70,000 Answer: B
_________________
5star rated online GMAT quant self study course See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews If you find one of my posts helpful, please take a moment to click on the "Kudos" button.



CEO
Joined: 03 Jun 2019
Posts: 2904
Location: India
GMAT 1: 690 Q50 V34
WE: Engineering (Transportation)

Re: (4.8*10^9)^(1/2) is closest in value to
[#permalink]
Show Tags
16 Sep 2019, 07:04
ske wrote: \(\sqrt{4.8*10^9}\) is closest in value to
(A) 2,200 (B) 70,000 (C) 220,000 (D) 7,000,000 (E) 22,000,000 \(\sqrt{4.8*10^9}\) is closest in value to \(\sqrt{4.8*10^9} = \sqrt{48 * 10^8} = 7 * 10^4 = 70,000\) IMO B
_________________
Kinshook Chaturvedi Email: kinshook.chaturvedi@gmail.com




Re: (4.8*10^9)^(1/2) is closest in value to
[#permalink]
16 Sep 2019, 07:04




