The average cell phone bill is $78 with a standard deviation of $10. What is the minimum percentage of cell phone bills that will be between $54 and $102.

we are given the mean which is $78 which is the average value of the data therefore this tells us most values are collectively around this bill and we also know the standard deviation of the cellphone bill which is $10 now we check the possibilities of x which is the cellphone bill being around these values so if x>$78+$10 , where x>$88 as we know the standard deviation is the measure of dispersion of data from the mean then we will see if x<$68 also then we'll find the probability where $68>x>$88 therefore if we sum these whole probabilities they will give us 1 which means it is certain but not impossible to find values that are $102>x>$54 which we see by the above numbers that approximately 1 is the probability which is 100%.