To answer this question, you must know what the standard deviation is.
The standard deviation is an index that measures the dispersion of a data set, while the largest is the standard deviation most dispersed are the data with respect to the mean value.
For a normal distribution, it is known that 68% of the data is not more than one standard desviation of the mean.
In this case, when they talk about -1 standard deviation of the mean.
Is:
average - 1 standard deviation
So
62 - 5.7 = 56.3
Therefore, the value sought is 56.3
