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When Mrs. JHixson gave a test, the scores were normally distributed with a mean of 78 and a standard deviation of 6. This means that 95% of her students scored between which two scores?


A. 72 and 84


B. 66 and 90


C. 60 and 96


D. 60 and 100

Respuesta :

For normal distribution 95% lie in the range mean-2*standard deviation for lower bound and mean+2*standard deviation for upper bound.

Upper bound  is 78+2*6=78+12=90
 Lower bound is 78-2*6=78-12=66
B. 66 and 90

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