Solve the problem.
-A collection of dimes is arranged in a triangular array with 15 coins in the base row, 14 in the next, 13 in the next, and so on with 1 dime in the last row. Find the value of the collection.
A)$1.20
B)$24.00
C)$12.00
D)$6.00

Question

Quizplus · Accepted Answer

The value of the collection can be found by first determining the total number of dimes in the triangular array. This is a sum of an arithmetic series with the first term $a_1 = 15$, the last term $a_n = 1$, and the number of terms $n = 15$. The sum of the series $S_n = \frac{n}{2}(a_1 + a_n) = \frac{15}{2}(15 + 1) = \frac{15}{2} \times 16 = 120$. Since each dime is worth $0.10, the total value is $120 \times $0.10 = $12.00$.

Solve the Problem. -A Collection of Dimes Is Arranged in a Triangular Array