The scores on an exam are normally distributed, with a mean of 74 and a standard deviation of 7. What percent of the scores are less than 81?
A. 84%

B. 13.5%

C. 50%

D. 16%

Question

The scores on an exam are normally distributed, with a mean of 74 and a standard deviation of 7. What percent of the scores are less than 81?
A. 84%
	
B. 13.5%
	
C. 50%
	
D. 16%

anonymous · Answer

HELP! I FORGOT HOW TO DO THESE! :(

matt101 · Answer

In a normal distribution, 50% of the data falls on either side of the mean, and 68% (34% on each side) of the data falls within 1 SD of the mean.

From your question, 81 is 1 SD above the mean. This means all the values less than 81 include the 50% of the data below the mean, and the additional 34% of the data between the mean and 1 SD above the mean. This means that 84% of all the data falls below 81 and A is your answer.

Hope that helps!

anonymous · Answer

thanks