28・15 A student recorded the exact percent frequency distribution of a set of measurements as shown in the table below:
But he forgot to mark the total number of measurements $N$, then the smallest possible value of $N$ is
(A) 5 .
(B) 8 .
(C) 16 .
(D) 25 .
(E) 50 .
(38th American High School Mathematics Examination, 1987)
[Solution] Given $12.5=\frac{1}{8}, 50=\frac{4}{8}, 25=\frac{2}{8}, \quad$ and $\frac{1}{8}+\frac{4}{8}+\frac{2}{8}+\frac{1}{8}=\frac{8}{8}=100 \%$, then the smallest possible value of $N$ is 8. Therefore, the answer is $(B)$.