Answer:
Does this sample provide convincing evidence that the machine is working properly?
Yes.
Step-by-step explanation:
<u>Normal distribution test:</u>
Where,
Once the significance level was not given, It is usually taken an assumption of a 5% significance level.
Taking the significance level of 5%, which means a confidence level of 95%, we have a z-value of
Therefore, we <u>fail to reject the null</u>. It means that the hypothesis test is not statistically significant: the average length is not different from 1.5!