SOLUTION: Directors of a mining company claim that 90% of the workforce supports a new shift pattern that they have suggested. A random survey of 100 people in the workforce finds 85 in favo

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Question 1187178: Directors of a mining company claim that 90% of the workforce supports a new shift pattern that they have suggested. A random survey of 100 people in the workforce finds 85 in favour of the new scheme. Test at 5% level of significance if there is difference between the survey results and the directors'claim.
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
Ho: p=0.9
Ha:p ne 0.9
alpha =0.05 p{reject Ho|Ho true}
test stat is a z
reject Ho for |z|>1.96
z=(phat-p)/sqrt (p*(1-p)/n)
=-0.05/sqrt(0.09/100)
=-0.05/0.03=-1.67
fail to reject Ho at 5% level. There is insufficient evidence to reject the claim.
p-value=0.096