What is the probability that an integer in the set \1, 2, 3, …, 100\ is divisible by 2 and not divisible by 3?

2003 AMC 10A Problem 15 — Solution

Attempt Problem 15 of the 2003 AMC 10A below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2003 AMC 10A solutions, or check the answer key.

All problems are used with official legal permission of the Mathematical Association of America (MAA).

15.

What is the probability that an integer in the set $\{1, 2, 3, \ldots, 100\}$ is divisible by $2$ and not divisible by $3?$

$\dfrac{1}{6}$

$\dfrac{33}{100}$

$\dfrac{17}{50}$

$\dfrac{1}{2}$

$\dfrac{18}{25}$

Of the $100$ integers, $50$ are divisible by $2.$

Among those, the ones also divisible by $3$ are the multiples of $6,$ of which there are $16.$

So $50 - 16 = 34$ qualify, giving probability $\dfrac{34}{100} = \dfrac{17}{50}.$

Thus, the correct answer is C.