One way of approaching the solution of this problem is to use the "z-score" formula. The z-score tells us how many s. d. a given point is above or below the given mean.
The formula for z score is as follows:
x-mean
z = --------------
s. d.
Thus, with mean =50 and std. dev. = 4, we get
x-mean 60-50
z = -------------- z = -------------- = 10/4 = 2.5
s. d. 4
Thus, 60 is 2.5 std. dev. above the mean, 50.
