A manufacturer makes three types of screws. Type A comes in a bulk pack of 1000 screws. Type B comes in a bulk pack of 500 screws. Type C comes in a bulk pack of 800 screws. Type A screws each have a probability of .001 of having a flaw. The probability is .003 for Type B and .005 for Type C.
(a) If a contractor buys one pack of each type of screws, find the expected total number of defective screws among the three packs.
(b) Find the probability that there are no more than 5 defective screws total among the three packs.
(c) Find the expected number of packs that have no more than 5 defective screws. (Your answer will be between 0 and 3.)

Step-by-step explanation:

Given that a manufacturer makes three types of screws

Type             A        B           CTotal

Pack         1000500  800  

P for flaw0.0010.030.005  

Pack*p                 115                    4     20

a) Expected total number of defective screws = 20

b) For one pack each no of defective screws =20

Hence for 5 expected number number of packs form each should be 1/3

if the eqn of the parabola is f(x) = (x-4)(x+2), we need to mult. this out to find the coordinates of the vertex.

then f(x) = x^2 + 2x - 4x - 8, and f(x) = x^2 - 2x - 8.

one way in which you can find the vertex is to calculate x = -b / (2a).   here, that comes to

        )

x = = 1.   f(1) = 1^2 - 2(1) - 8 = - 9.   vertex is at (1, -9).

        2(1) 

find another point on the curve:   let x=0, for which y=-8.   then (0, -8) is on the curve.   plot the vertex and this point and draw a smooth parabola thru both.

hope this

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step-by-step explanation: