DR CHUNG HELP! [TIP 4 - Classifying a group in 2 different ways]

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1

Can someone please help me understand tip 4 because i can’t wrap my head around it. Heres an example:

  1. On a college faculty, 4/7 of professors are male, and the ratio of professors older than 50 to the professors less than or equal to 50 is 2:5. If 1/5 of the male professors are older than 50, what is the fraction of the female professors who are less than or equal to 50?

Mind = Blown

2

I don’t have Dr. Chung’s but…

This problem is easily solved by making a small 2x2 table and categorizing M/F and older/younger than 50. You can assume that there are 70 professors (I picked this # since it’s an easy multiple of 7). After this, fill in the table, and read carefully. I got 3/5 as the answer, assuming I didn’t mess up.

Edit: I originally messed up - which is why reading carefully is crucial. But the wording of that last phrase is awkward.