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# I need help...

How do I find the variable "P" if the interest rate is 6% the time is 3 years and the simple interest is \$2952?

### 3 Answers by Expert Tutors

Pam J. | Veteran teacher; all mid. sch. subjects; high sch. science; readingVeteran teacher; all mid. sch. subjects;...
5.0 5.0 (54 lesson ratings) (54)
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hi ben

I took the simple interest- 2952 and divided it by 3 years= 984- so you are getting 984.00 interest per year

then take the 984 you get each year and divide it by your interest rate =0.06 and you get 16,400

to check yourself-- take 16,400 and multiply it by 0.06 and you get 984 (the interest you get each year) and multiply it by 3 years and you get 2952--total interest

You can also do it this way: take the total interest 2952 and divide it by the interest rate 0.06 and you get 49,200, then divide that by 3 years and you get 16,400= principal
Steve S. | Tutoring in Precalculus, Trig, and Differential CalculusTutoring in Precalculus, Trig, and Diffe...
5.0 5.0 (3 lesson ratings) (3)
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Find the variable "P" if the interest rate is 6%, the time is 3 years, and the simple interest is \$2952.

simple interest earned = P I T

\$2,952 = (P dollars)*(6% / year)*(3 years)

\$2,952 = (P dollars)*(18%)

18% = 18 per centum (Latin for hundred) = 18/100 = 0.18

P = \$2,952/0.18 = \$16,400
Kay G. | ~20 Years Accounting Tutoring Experience~20 Years Accounting Tutoring Experience
4.9 4.9 (32 lesson ratings) (32)
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So that you can remember how to do this for any problem, recall that I = PRT.

To solve for the other ones there's a pattern:

P = I / (RT)
R = I / (PT)
T = I / (PR)

Notice that each one is the I divided by the other two numbers.  Make sure you do the denominator first.

So for this:
P = 2952 / (.06*3)
P = 2952 / .18
P = 16,400

What you're actually doing is working that original equation backwards.  If you multiply to get there, you divide to go backwards.