The average score on a standardized test is 750 points with a standard deviation of 50 points. If 2,000 students take the test at a local school, how many students do you expect to score between 700 and 750points? Answer 680 700 720 740

Question

The average score on a standardized test is 750 points with a standard deviation of 50 points. If 2,000 students take the test at a local school, how many students do you expect to score between 700 and 750points? Answer 		 680 		 700 		 720 		 740

anonymous · Answer

It helps to look at an example of a normal distribution with standard deviations to solve this problem. Check out this image from wikipedia: http://upload.wikimedia.org/wikipedia/commons/8/8c/Standard_deviation_diagram.svg. The students who scored between 700 and 750 were within one deviation below the average. If you look at the graph, you will see that this equates to 34% of the students. So, we multiply .34 * 2000 (total number of students) Answer is 680.