12th edition OG problem.

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12th edition OG problem.

by Aishwarya1204 » Fri Oct 19, 2012 5:07 am
On a scale that measures the intensity of a certain phenomenon, a reading of n+1 corresponds to an intensity that is 10 times the intensity corresponding to a reading of n. On that scale, the intensity corresponding to a reading of 8 is how many times as great as the intensity corresponding to a reading of 3?

a) 5
b) 50
c) 10(power 5)
d) 5(power 10)
e) 8(power 10)-3(power 10)

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by Anurag@Gurome » Fri Oct 19, 2012 5:25 am
Aishwarya1204 wrote:On a scale that measures the intensity of a certain phenomenon, a reading of n+1 corresponds to an intensity that is 10 times the intensity corresponding to a reading of n. On that scale, the intensity corresponding to a reading of 8 is how many times as great as the intensity corresponding to a reading of 3?

a) 5
b) 50
c) 10(power 5)
d) 5(power 10)
e) 8(power 10)-3(power 10)
Reading of n+1 corresponds to an intensity that is 10 times the intesity corresponding to a reading of n means every number on the scale is 10 times the previous number.
So, we can say that f(n + 1) = 10 * f(n)
Let us assume that the intensity corresponding to a reading of 3 be X, then f(3) = X
So, f(4) = 10 * f(3) = 10X
f(5) = 10 * f(4) = 10² * f(3)
f(6) = 10^3 * f(3) and so on
Hence, f(8) = 10^5 * f(3) = 10^5 * X

The correct answer is C.
Anurag Mairal, Ph.D., MBA
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