Hi, I'm having a little trouble with this question:(adsbygoogle = window.adsbygoogle || []).push({});

Among entering students at a certain college, the men averaged 650 on the Math SAT, and their SD was 125. The women averaged 600, but had the same SD of 125. There were 500 men in he class, and 500 women.

Q) For the men and the women together, was the SD of Math SAT scores less than 125, just about 125, or more than 125?

I'm not quite sure how to solve this. By looking at the question, I thought the SD would stay the same. Then I pictured a normal curve for men, women, and combined, and since the combined average is 625, the SD seemed to be larger because the combined curve had to take care of the extremes of both men and women. Then out of desperation, I tried finding the pooled Standard Deviation and found it to be 125.

I'm just going around in circles, not knowing exactly what I'm doing. I think it's either more than 125 or equal to 125, but even if one of those were right, I'm not confident on the reasoning behind it. Can you please help me solve this question, and future questions like these?

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# Combined Standard Deviation

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