Pam J. answered • 02/12/14

Veteran teacher; all mid. sch. subjects; high sch. science; reading

Ben H.

asked • 02/11/14How do I find the variable "P" if the interest rate is 6% the time is 3 years and the simple interest is $2952?

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Pam J. answered • 02/12/14

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Veteran teacher; all mid. sch. subjects; high sch. science; reading

hi ben

my answer is P=16,400

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. answered • 02/12/14

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Tutoring in Precalculus, Trig, and Differential Calculus

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

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.

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