Question 5 (1 mark) Attempt 1 The drying time of a certain type of paint under s

Question

Question 5 (1 mark) Attempt 1 The drying time of a certain type of paint under specified test conditions is known to be normally distributed with mean value 76 min and standard deviation 9.9 min. Chemists have proposed a new additive designed to decrease average drying time. It is believed that drying times with this additive will remain normally distributed with standard deviation 9.9 min. Because of the expense associated with the additive, evidence should strongly suggest an improvement in average drying time before such a conclusion is adopted. Let u be the true average drying time when the additive is used. The hypothesis are to be tested using a random sample of 25 observations. The rejection region is: Find the minimum value of c that yields a test with significance 0.05? Za a(tail area) 0.1 0.05 0.025 0.01 0.005 0.001 %ile w

Explanation / Answer

Ans:

Significance level=0.05

critical z value=normsinv(0.05)=-1.645

Rejection region:

x-bar<=76-c

where,

c=1.645*9.9/sqrt(25)=3.2571

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