Posted by Tina on .
10,000 students took a math test. If there average score was 40 with standard deviation of 10, how many students must have scored between 20 and 40 marks?
3,772
2,227
5,000
3,334
4,772

Steve help! 
Steve,
20 is 2 std's out
2 std's is 47.7%
So, I'd pick 4772