A record club has found that the marginal profit, Upper P prime (x ), in cents, is given by

Upper P prime (x )equals negative 0.0008 x cubed plus 0.20 x squared plus 46.8 x for x less than or equals 200,

where x is the number of members currently enrolled in the club. Approximate the total profit when 120 members are enrolled by computing the sum

Summation from i equals 1 to 6 Upper P prime (x Subscript i Baseline )Upper Delta x with Upper Delta x equals 20.