Answer:
d) 2.3 to 3.5
Explanation:
In this problem, we have that:
The mean is 2.9
The standard deviation is 0.6
One standard deviation below the mean
This is the mean subtracted by one standard deviation.
So this is 2.9 - 0.6 = 2.3
One standard deviation above the mean
This is one standard deviation added to the mean.
So this is 2.9 + 0.6 = 3.5
So the correct answer is:
d) 2.3 to 3.5