2025 AMC 8 Problems/Problem 13

Revision as of 23:01, 29 January 2025 by Mrtnvlknv (talk | contribs) (Solution)

Problem

Each of the even numbers $2, 4, 6, \ldots, 50$ is divided by $7$. The remainders are recorded. Which histogram displays the number of times each remainder occurs?


Solution

Writing down all of the numbers modulo $7$, we have $2, 4, 6, 1, 3, 5, 0, 2, \ldots, 4, 6, 1$. Notice how the the cycle $2, 4, 6, 1, 3, 5, 0$ repeats itself 3 times (because $\lfloor{\frac{50}{14}}\rfloor=3$). Then, we have $44$, $46$, $48$, and $50$ remaining, which are $2$, $4$, $6$, and $1$ mod 7, respectively. After adding them to our total count, the remainder $0$ occurs $3$ times, $1$ occurs $4$ times, $2$ occurs $4$ times, $3$ occurs $3$ times, $4$ occurs $4$ times, $5$ occurs $3$ times, and $6$ occurs $4$ times, which corresponds to histogram $\boxed{\text{(A)}}$.

~mrtnvlknv