A report states that the cost of repairing a hybrid vehicle is falling even whil

Question

A report states that the cost of repairing a hybrid vehicle is falling even while typical repairs on conventional vehicles are getting more expensive. The most common hybrid repair, replacing the hybrid inverter assembly, had mean repair cost of $3, 927 in 2012. Industry experts suspect that the cost will continue to decrease given the increase in the number of technicians who have gained expertise on fixing gas-electric engines in recent months. Suppose a sample of 100 hybrid inverter assembly repairs completed in the last month was selected. The sample mean repair cost was $3, 840 with the sample standard deviation of $300 Complete parts (a) and (b) below. A. Reject the null hypothesis. There is sufficient evidence at the 0.05 level of significance that the population mean cost is less than $3, 927. B. Do not reject the nut hypothesis There is insufficient evidence at the 0.05 level of significance that the population mean cost is less than $3, 927. C. Do not reject the null hypothesis There is insufficient evidence at the 0.05 level of significance that the population mean cost is greater than $3, 927. D. Reject the null hypothesis. There is sufficient evidence at the 0.05 level of significance that the population mean cost is greater than $3, 927. b. Determine the p-value and interpret its meaning. The p-value is[]

Explanation / Answer

here null hypothesis:mean =3927

alternate hypothesis:mean <3927

std error =std deviation/(n)1/2 =30

hence test stat t=(X-mean)/std errror =(3840-3927)/30=-2.9

for abvoe test stat t ' p value =0.002

please reply as I have considered it as t distribution,

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