<p>Of the 240 campers at a summer camp, 5/6 could swim. If 1/3 of the campers took climbing lessons, what was the least possible number of campers taking climbing lessons who could swim?</p>
<p>A. 20
B. 40
C. 80
D. 120
E. 200</p>
<p>I got the answer right using a pseudo guess and finding the greatest common factor (I dont know why I did this...maybe somebody can explain to me if my process was legit and why). I won't tell you the answer here because I'm looking for an explanation as to how to do it. Thanks!</p>
<p>i'll say B</p>
<p>because</p>
<p>5/6 could swim, right? that means that 200 could swim, and 40 could NOT.</p>
<p>also, 1/3 took climbing lessons. that means 80 took climbing lessons.</p>
<p>now, you asked what was the least number of campers taking climbing lessons who could swim?</p>
<p>well, just subtract 40 from the number of campers taking climbing lessons.</p>
<p>you get 40. so B.</p>
<p>am i right?</p>
<p>yes, but why subtract 40?</p>
<p>hm or maybe is it because if there are 200 that can swim and 80 that can climb...200+80=280. There are only 240 people in the camp. That means there is an overlap in the 200 and 80 group. So 280-240=40?</p>
<p>Imagine the venn diagram..</p>
<p>i'm not going to try to understand what you did, it seems more complicated than what i did.</p>
<p>you subtract 40 because that is the MOST amount people who can NOT swim. </p>
<p>are you still confused?</p>
<p>see, if 200 ppl can swim, there are forty who cannot. 80 can climb. to find out least poss who do both, assume that all of the remaining (those who dont swim) can climb.</p>
<p>that leaves 40 who do both. and thts the minimum.</p>