Question

22-23

D Question 22 4 pts Injection molding. Refer to this problem description for the next couple questions Two different types of injection-molding machines are used to form plastic parts. A part is considered defective if it has excessive shrinkage or is discolored. Two random samples, each of size 300, are selected, and 17 defective parts are found in the sample from machine 1, while 12 defective parts are found in the sample from machine 2 Is it reasonable to conclude that both machines produce the same proportion of defective parts, using a -0.05? What is the test statistic, 20. for this hypothesis test? Round your answer to 3 decimal places leg. 98.765). Question 23 2 pts Refer to the injection molding problem description above reasonable to conclude that both machines produce the same proportion of defective parts

Answer 1

22)

x1                =	17	x2                =	12
p̂1=x1/n1 =	0.0567	p̂2=x2/n2 =	0.0400
n1                       =	300	n2                       =	300
estimated prop. diff =p̂1-p̂2    =		0.0167
pooled prop p̂ =(x1+x2)/(n1+n2)=		0.0483
std error Se=√(p̂1*(1-p̂1)*(1/n1+1/n2) =		0.0175
test stat z=(p̂1-p̂2)/Se =		0.952

(please try 0.954 if this comes wrong due to rounding error)

23)

it is reasonable to conclude that,,,,,,,,,,,,