Answer:
The standard deviation is 1.5 inches.
Step-by-step explanation:
For a normal curve, we have that the area between the mean and the mean plus two times the standard deviation is something around 47.5%
Then the area between the mean minus two times the standard deviation and the mean plus two times the standard deviation is equal to the 95%.
the mean is 66
if the standard deviation is x, we have that:
66 + 2*x = 69
66 - 2*x = 63
then we can find that:
2*x = 66 - 63 = 3
x = 3/2 = 1.5
The standard deviation is 1.5 inches.
The standard deviation for the given group when the mean should be 66 inches so it should be considered as the 1.5 inches.
Since
For the normal curve, the area between the mean and the mean plus two times the standard deviation should be around 47.5%
So the area between the mean minus two times the standard deviation and the mean plus two times the standard deviation is equal to the 95%.
the mean is 66
In the case when the standard deviation is x
So,
66 + 2*x = 69
66 - 2*x = 63
So,
2*x = 66 - 63 = 3
x = 3/2
= 1.5
hence, The standard deviation is 1.5 inches.
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