Answer:
The test is left - tailed
We cannot reject the organization's claim ( its cheapest screens will truly last less than 2.8 years)
Step-by-step explanation:
Sample size, n = 61
Sample mean,
Standard deviation,
Significance level, α=0.02
Null hypothesis,
Alternative hypothesis,
It is clearly seen from the alternative hypothesis, that it is a left tailed test. It is not tailed towards the two directions.
Calculate the test statistic:
Calculate the P-value:
P(Z < -3.35) = 0.0002
Since (p-value = 0.0002) < (α=0.02), the null hypothesis is rejected.
It can therefore be concluded that the mean of the cheapest screen is less than 2.8 years. i.e. the cheapest screen will last less than 2.8 years