##### pls solve my precalculus word problem. ASAP. Use steps below to solve.

 Mathematics Tutor: None Selected Time limit: 1 Day

The Richter scale is used to measure the magnitude of a earthquake. The magnitude, R, is given by the equaiton R=0.65log(0.39E)+1.45, where E is the energy (measured in kilowat hours)released by the earthquake. Determine the amount of energy released by an earthquake of magnitdude 7.5

USE THESE STEPS TO SOLVE:

a. Rewrite equation for magnitude of earthquake, using magnitude of 7.5 given in problem.

b. Simplify so it is writen in form b=loga

c.solve problem for E, the energy released in earthquake.

Sep 1st, 2015

a. You're given the main equation where R is the magnitude of the earthquake.  This part just asks you to substitute 7.5 in for R in the main equation:

R=0.65log(0.39E)+1.45

7.5=0.65log(0.39E)+1.45

b. Now you need to simplify the expression into the form b=loga

6.05=0.65log(0.39E)   Subtracted 1.45 from both sides of equation.

9.31=log(0.39E)          Divided each side by 0.65.  That's the answer to part b.

c. To solve for E, you need to get the E out from within the log function.  You can use a simple 'log rule' to do this:

General rule:

log(x)=N can be rewritten as 10^N=x

To rewrite the main equation:

9.31=log(0.39E)

10^(9.31)=0.39E

E=5.24*10^9 kilowatt hours

Sep 1st, 2015

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Sep 1st, 2015
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Sep 1st, 2015
Dec 6th, 2016
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