To find the 80th percentile, you have to use one of the inverse CDF functions. NORM.DIST is not one of them; it returns a probability. The 80th percentile the value of the random variable for which 80% of the distributions falls below that value.
NORM.INV(0.80, 475, 33) returns what you want.
NORM.S.INV could also work, but not with the given arguments. NORM.S.INV(0.80) alone will give you the 80th percentile for the standard normal distribution (mean 0, standard deviation 1), approximately 0.8416. From here, you would convert this value to the given distribution using
so that
NORM.INV gives this value directly.
Given:
It is given that surface area must be less than 150 cm².
Solution:
The Maximum Volume With Total Surface Area Less than 150 cm² is shown in the table.
From the table, it can be concluded that for r=3.00 cm and h=4.95 cm the surface area will be less than 150 cm² and the volume will be the maximum.
Calculate the volume.
Hence, the required dimensions are r=3.00 cm and h=4.95 cm.
