solve pls: number of club members for maximum revenue

Submitted by Juny Geraldizo… on

A student club on a college charges monthly membership dues of P10, less 5 centavos for each member over 60. How many members would give the club, the most revenue from the monthly dues?

Jhun Vert Fri, 04/29/2016 - 06:24

Let
R = monthly revenue
x = number of student-member in excess of 60
x + 60 = total number of student-member

For number of members ≤ 60
monthly dues for each member = P10

For number of members > 60
monthly dues for each member = P(10 - 0.05x)

R=(10−0.05x)(60+x)

R=600+7x−0.05x2

dRdx=7−0.1x=0

x=70

total number of members = 70 + 60 = 130       answer