(From 5lb p.597)

I attempted to use some logic from one of Greg’s average videos to solve this.

I took the average of the women’s heights and the average of the men’s heights and found the average of those two averages (66 + 72) / 2 = 69. The purpose of this was to see if the result is above, below, or equal to 70 (the average height of all ppl in the group). If the result were 70, then the ratio is 1:1.

But since 69 is less than 70, then to get the average to 70, there has to be a man/men added. So the ratio would tip in the men’s favor, there would be fewer women than men.

The only option choice in which there are fewer women is B, 1:2. This is the right answer, but did I just get lucky? Was my logic flawed? 5 lb explanation says use algebra and it’s kind of time consuming.