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missrochelle
- Master | Next Rank: 500 Posts
- Posts: 117
- Joined: Wed Jun 09, 2010 7:02 am
Someone pls tell me what I'm missing here --
OG #28. The average distance between the sun and a certain plant is approximately 2.3 x 10^14 inches. Which of the following is closes to the the average distances in kilometers? (1 kilometer is approximately 3.9 x 10^4 inches).
A) 7.1 x 10^8
B) 5.9 x 10^9
C) 1.6 x 10^10
D) 1.6 x 10^11
E) 5.9 x 10^11
OA: B
I cross multiplied , ending up with:
2.3/3.9 x 10^10 this is correct
then estimated 2/4 * 10^10 again--- correct
back to decimal form since that's the format of the answer choices .... gives me .5 x 10^10
this is where i get lost.
in order to convert .5 to 5, you have to factor the expression by 10^1. That gives me E .
Please explain how 10^-1 times .5 = 5. I have re-read the rules over and over and i get .5 * 10^-1 (move 1 decimal to the left) leads me to .05.
OG #28. The average distance between the sun and a certain plant is approximately 2.3 x 10^14 inches. Which of the following is closes to the the average distances in kilometers? (1 kilometer is approximately 3.9 x 10^4 inches).
A) 7.1 x 10^8
B) 5.9 x 10^9
C) 1.6 x 10^10
D) 1.6 x 10^11
E) 5.9 x 10^11
OA: B
I cross multiplied , ending up with:
2.3/3.9 x 10^10 this is correct
then estimated 2/4 * 10^10 again--- correct
back to decimal form since that's the format of the answer choices .... gives me .5 x 10^10
this is where i get lost.
in order to convert .5 to 5, you have to factor the expression by 10^1. That gives me E .
Please explain how 10^-1 times .5 = 5. I have re-read the rules over and over and i get .5 * 10^-1 (move 1 decimal to the left) leads me to .05.
