1971 AHSME Problems/Problem 4

Revision as of 09:37, 1 August 2024 by Thepowerful456 (talk | contribs) (see also box, minor formatting changes)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

Problem

After simple interest for two months at $5$% per annum was credited, a Boy Scout Troop had a total of $\textdollar 255.31$ in the Council Treasury. The interest credited was a number of dollars plus the following number of cents

$\textbf{(A) }11\qquad \textbf{(B) }12\qquad \textbf{(C) }13\qquad \textbf{(D) }21\qquad  \textbf{(E) }31$

Solution

We can use the formula $A = P(1+rt)$ for simple interest, where $P$ is the principal (initial amount), $A$ is the total, $r$ is the interest rate per year, and $t$ is the time in years.

We are solving for $P,$ so we can rearrange the equation: \[P = \frac{A}{1+rt}\] Plug in all the necessary numbers: \[P = \frac{255.31}{1 + (0.05)(2/12)} = \textdollar 253.21\] So, the interest is \[P*(0.05)(2/12) = \textdollar 2.11\]

The answer is $\boxed{\textbf{(A) }11}$

-edited by Happypuma46

If there are any mistakes, feel free to edit so that it is correct.

See Also

1971 AHSC (ProblemsAnswer KeyResources)
Preceded by
Problem 3
Followed by
Problem 5
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
All AHSME Problems and Solutions

The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions. AMC logo.png