Question

Suppose that a certain website claims that it averages 4.7 hours of downtime per month. (Downtime is time that the site is not available.) 
In a random sample of 17 months, the average downtime was 4.9 hours per month, with a standard deviation of 0.5 hours per month. What is the z-value rounded to the nearest hundredth?  Is there enough evidence to reject the claim?​

Answer 1

Answer:

The z-value rounded to the nearest hundredth is -1.64

There is no enough evidence to reject the claim.

Step-by-step explanation:

A certain website claims that it averages 4.7 hours of downtime per month.

No. of samples = n = 17

Mean =$\mu = 4.9$

Standard deviation =$\sigma = 0.5$

Formula: $Z=\frac{x-\mu}{\frac{\sigma}{\sqrt{n}}}$

$Z=\frac{4.7-4.9}{\frac{0.5}{\sqrt{17}}}$

Z =−1.64

Z critical at 90% is 1.65

Since Z calculated < Z critical

So, there is no enough evidence to reject the claim.