Source: Official Guide for the GMAT 13th Ed. Problem Solving; #65 Official Guide for the GMAT 2015 14th Ed. Problem Solving; #65

3

The average distance between the Sun and

The average distance between the Sun and a certain planet is approximately 2.3x10 inches. Which of the following is closest to the average distance between the Sun and the planet, in kilometers? (1 kilometer is approximately 3.9x10 inches.)

4 Explanations

1

Felipe Levi Gurgel

I approached differently

I converted 2.3 x 10 ^14 to: 230 x 10^12. I changed the other to 39 x 10^3.

Than, I approach 230/39 is close to 240/40 which is 6. Than the answer would be 5.9.

Tha 10^12 - 10^3 = 10^9.

This resulted in 6 x 10^9. Which is closest to 5.9 x 10^9.

Dec 8, 2016 • Comment

Cydney Seigerman, Magoosh Tutor

Nice work, Felipe. You've shown another effective way to approximate the answer :D

Dec 9, 2016 • Reply

1

Chitrabhanu Dasgupta

What I thought, when dividing the number, I was getting a number as (2.3/3.9) * 10 ^10

2.3/3.9 seems to be point something, so if we have multiply that by 10 it will be something point something, mostly a (single digit.single digit)

And offsetting that 10 multiplication I get 10^9 as the multiplier from 10^10. Only one answer with 10^9 i.e. b

Feb 8, 2016 • Comment

Cydney Seigerman, Magoosh Tutor

Great job with this approximation! Thanks for sharing your way of solving the problem :)

Feb 8, 2016 • Reply

1

James Plewak

I approached this a little differently and wanted to make sure it is acceptable.

I converted 2.3 x 10 ^14 to: 24 x 10^13. I changed the other to 4 x 10^4.

This resulted in 6 x 10^9. Which is closest to 5.9 x 10^9.

Jun 6, 2015 • Comment

Jonathan , Magoosh Tutor

James, that's a great way to do this. No other choices are close enough to 5.9 x 10^9, so you can be confident you're correct. Excellent job approximating effectively!

Jun 15, 2015 • Reply

3

Gravatar Mike McGarry, Magoosh Tutor

Dec 27, 2013 • Comment

Nice curiosity about Jupiter! :D

Jan 25, 2015 • Reply

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