# Math Help - How good is this score? (Standard deviation problem)

1. ## How 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?

2. ## Re: 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.

3. ## Re: 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.