SOLUTION: A teacher is comparing test grades for a yearly test in her Algebra class. The mean of the scores is 78% and has a standard deviation of 3.8. Which range gives the set of values

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Question 1041478: A teacher is comparing test grades for a yearly test in her Algebra class. The
mean of the scores is 78% and has a standard deviation of 3.8. Which range gives the set of values that are within two standard deviations of the mean?
A.) 74.2 - 81.8
B.) 70.4 - 85.6
C.) 74.2 - 85.6
D.) 70.4 - 81.8
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
mean = 0.78
standard deviation = 0.038

lower bound = 0.78-2*0.038 = 0.704 = 70.4%
upper bound = 0.78+2*0.038 = 0.856 = 85.6%

So the final answer is choice B