Hypothesis testing for single mean.
Assume that the measurements came from a normal distribution. The variability of the manufacturing process is unknown means the same as the standard deviation is unknown.
Auto crank shafts. Here are measurements (in millimeters) of a critical dimension for 16 auto engine crankshafts:
224.120

224.001

224.017

223.982

223.989

223.961

223.960

224.089

223.987

223.976

223.902

223.980

224.098

224.057

223.913

223.999



The dimension is supposed to be 224 mm and the variability of the manufacturing process is unknown. Is there evidence that the mean dimension is not 224mm?
1. The appropriate test to use is
a. TTest b. 1PropZtest c. ZTest d. Paired T test
2. The appropriate type of test to use based on the tails of the distribution
a. Lefttailed b. Twotailed c. Righttailed
3. The pvalue of the test is closest to
a. 0.9289 b. 0.0431 c. 0.0134 d. 0.9019
4. Based on the above analysis (pvalue and α= 0.025), we conclude that
a. The mean dimension of crankshafts is 224mm.
b. The mean dimension of crankshafts is 224mm.
c. We do not have sufficient information to draw a conclusion