The average score for the exam was 100 with a standard deviation of 10. A person takes the exam and scores 121. Assuming that the exam is valid, how good is this score?

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- Apr 6th 2014, 11:50 AMineedhelplzHow good is this score? (Standard deviation problem)
The average score for the exam was 100 with a standard deviation of 10. A person takes the exam and scores 121. Assuming that the exam is valid, how good is this score?

- Apr 6th 2014, 04:14 PMinfkelsierRe: How good is this score? (Standard deviation problem)
are we told anything about the distribution of the results?

I will assume for now that the results are normally distributed.

Using this you can give a percentile value which is a way of showing "how good" the score is. - Apr 6th 2014, 05:13 PMHallsofIvyRe: How good is this score? (Standard deviation problem)
121- 100= 21. 21/10= 2.1. Use a table of the standard normal distribution to determine the probability of a standard score of 2.1.