The grades on the last history exam had a mean of 80%. assume the population of grades on history exams is known to be normally distributed with a standard deviation of 5. what percent of students earn a score between 70% and 80%?

Step-by-step explanation:

We assume the population of grades on history exams is known to be normally distributed.

Given : Population mean :

Standard deviation :

Let x be the random variable that represents the grades on history exams  .

Z-score :

For x= 0.70

For x=0.80

By using the standard normal distribution table , the probability of students earn a score between 70% and 80% will be :_

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step-by-step explanati∵∵∴∴on: