Which represents a quadratic function?
f(x) = −8x3 − 16x2 − 4x
f (x) = x 2 + 2x − 5
f(x) = + 1
f(x) = 0x2 − 9x + 7

An office supply company conducted a survey before marketing a new paper shredder designed for home use. in the survey, 80 % of the people who tried the shredder were satisfied with it. because of this high satisfaction rate, the company decided to market the new shredder. assume that 80 % of all people are satisfied with this shredder. during a certain month, 100 customers bought this shredder. find the probability that of these 100 customers, the number who are satisfied is 69 or fewer.