The scores on a standardized test are normally distributed with a mean of 80 and standard deviation of 5. What test score is 0.9 standard deviations above the mean?

84.5

Step-by-step explanation:

Given :

Mean μ = 80

Standard deviation, σ = 5

Z = number of standard deviations from the mean, Z = 0.9

Teat score, x

Using the Zscore formula :

Zscore = (x - μ) / σ

Plugging in our values :

0.9 = (x - 80) / 5

Cross multiply

0.9 * 5 = x - 80

4.5 = x - 80

4.5 + 80 = x

x = 84.5

Test score = 84.5

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