Question 1199334
mean is 33 months.
standard deviation is 4 months.
guarantee is for 24 months.
z = (x - m) / s = (24 - 33) / 4 = -2.25
z is the z-score
x is the test score to be compared to the mean
m is the mean
s is the standard deviation
the guarantee is for 24 months.
if it last longer than 24 months, then the battery doesn't have to be replaced under guarantee.
if it last less than 24 months, then it will have to be replaced under guarantee.
the area to the left of a z-score of -2.25 is equal to .0122244334.
that's equal to 1.22% rounded to 2 decimal points.
that's the percent of batteries sold that would have to be replaced under guarantee.