# Math help needed: What is the principal? #2

Anonymous
account_balance_wallet \$5

### Question Description

If the accumulated amount is \$3,720 at the end of 3 years and the simple rate of interest is 8%/year, what is the principal?
 A. The principal is \$3,500. B. The principal is \$3,360. C. The principal is \$3,000. D. The principal is \$3,200.

DrMath
School: UC Berkeley

We just need to use the following expression:

F=P(1 + r*t)

So first, we solve for P by dividing by (1+ r*t) from both sides like this.

F /(1+r*t) = P*(1+r*t)/(1+r*t)   ------------->  F/(1+r*t) = P ----------------->   P = F/(1+r*t)

So we know: F = \$3,720  ;   t = 3 years    ;    r = 8% / year = 8/100 = 0.08 (in decimal form)

Then we enter 3,720 in place of I, 3 in place of t, and 0.08 in place of r into the equation.

P = 3,720/(1+0.08*3) = 3,720/(1+0.24) =3,720/1.24 =  3000

Final answer:  P = \$ 3000   (so it's option C).

flag Report DMCA
Review

Anonymous
awesome work thanks

Brown University

1271 Tutors

California Institute of Technology

2131 Tutors

Carnegie Mellon University

982 Tutors

Columbia University

1256 Tutors

Dartmouth University

2113 Tutors

Emory University

2279 Tutors

Harvard University

599 Tutors

Massachusetts Institute of Technology

2319 Tutors

New York University

1645 Tutors

Notre Dam University

1911 Tutors

Oklahoma University

2122 Tutors

Pennsylvania State University

932 Tutors

Princeton University

1211 Tutors

Stanford University

983 Tutors

University of California

1282 Tutors

Oxford University

123 Tutors

Yale University

2325 Tutors