Answer:
Option a) 50% of output expected to be less than or equal to the mean.
Step-by-step explanation:
We are given the following in the question:
The output of a process is stable and normally distributed.
Mean = 23.5
We have to find the percentage of output expected to be less than or equal to the mean.
Mean of a normal distribution.
- The mean of normal distribution divides the data into exactly two equal parts.
- 50% of data lies to the right of the mean.
- 50% of data lies to the right of the mean
Thus, by property of normal distribution 50% of output expected to be less than or equal to the mean.
Answer:
The appropriate null hypothesis is
The appropriate alternative hypothesis is
Step-by-step explanation:
Exactly a year prior to this poll, in June of 2004, it was estimated that roughly 1 out of every 4 U.S. adults believed (at that time) that the war in Iraq was the most important problem facing the country.
At the null hypothesis, we test if the proportion is still the same, that is, of . So
We would like to test whether the 2005 poll provides significant evidence that the proportion of U.S. adults who believe that the war in Iraq is the most important problem facing the U.S. has decreased since the prior poll.
Decreased, so at the alternative hypothesis, it is tested if the proportion is less than 0.25, that is: