What is the probabilty of a student scoring less than 77 on the test? Write your answer as a percent

Question

Scores on a English test have average of 85 with standard deviation of 8. What is the probabilty of a student scoring less than 77 on the test? Write your answer as a percent

Answer 1

So 85 is the mean, and 77 is one standard deviation below the mean. 68% of the distribution is between -1 and 1 standard deviation, so 34% is between -1 standard deviation (77) and the mean (85). Then another 50% of the distribution is above the mean. So 34% + 50%.