The diameters of cylinders form a normal distribution with the mean of 5cm and the standard deviation of 0.2cm. Katie ordered a cylinder from this population and the store manager told her that the cylinder she ordered is bigger than average in size. The manager specifically mentioned that her cylinder would be in the upper 10% in its size (diameter). What is the possible lowest diameter of Katie's cylinder
exactly you go it
p = 6s
hello from mrbilldoesmath!
(7 x + 6 y) (49 x^2 - 42 x y + 36 y^2)
the trick is to recognize that 343 = 7^3 and 216 = 6^3 and, in general,
a^3 + b^3 = (a + b) (a^2 - a b + b^2).
in our case
343x^3+216y^3 = (7x)^3 + (6y)^3
so take a = 7x and b = 6y in the above equation to get the answer.