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Is the average capacity of batteries less than 120 ampere-hours? A random sample of 49 batteries...

Is the average capacity of batteries less than 120 ampere-hours? A random sample of 49 batteries had a mean of 118.47 and a standard deviation of 3.66. Assume a normal distribution. Test at the 0.1 level of significance. (USING Z TABLE)

Math   Statistics-And-Probability   
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Answer #1

The null and alternative hypothesis is ,

The test is one-tailed test.

The test statistic is ,

The critical value is ,

; Fom Z-table

Rejection Rule : Reject Ho , If Z-stat<-1.28

Decision : Here , Z-stat=-2.93<-1.28

Therefore , reject Ho.

Conclusion : Hence , there is sufficient evidence to support the claim that the average capacity of batteries less than 120 ampere-hours.

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