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 :_

x=-2

infinite number of lines, so there is an infinite number of equations.

step-by-step explanation:

there are an infinite number of line that passes through the point (-2,5)

x=-2   is one line that passes through the point

y = 5 is another line that passes through the point

(these two lines are perpendicular to each other).

since the number of   numbers are infinite and the slope is the ratio of two numbers,(change in y over change in x) we can have an infinite number of slopes.     our only condition is that it passes through the point (-2,5)