Assume that a set of test scores is normally distributed with a mean of 70 and a standard deviation of 10. In what percentile is a score of 65?

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Answer:

30.85%

Step-by-step explanation:

Assume that a set of test scores is normally distributed with a mean of 70 and a standard deviation of 10

mean = 70 and SD= 10

To find percentile we use z-score value

z value can be find using formula

[tex]z= \frac{x-mean}{SD}[/tex]

[tex]z= \frac{65-70}{10}[/tex]

z=-0.5

Now we use z- score table to find the value when z=-0.5

P(x=65) = 0.3085

To find percentile we multiply by 100

0.3085 * 100 = 30.85%