Question 1141589
mean is 127.8
standard deviation is 1.8


z-score for 86 percent to the left of it is 1.08031934.


z-score formula is z = (x-m)/s


in this case:


z = 1.08031934
m = 127.8
s = 1.8.


z-score formula becomes 1.08031934 = (x-127.8)/1.8


solve for x to get x = 1.08031934 * 1.8 + 127.8 = 129.7445748.


round to 1 decimal point equals 129.7.


that should be your solution.