Answer:
Option A) One tailed test is a hypothesis test in which rejection region is in one tail of the sampling distribution
Step-by-step explanation:
One Tailed Test:
- A one tailed test is a test that have hypothesis of the form

- A one-tailed test is a hypothesis test that help us to test whether the sample mean would be higher or lower than the population mean.
- Rejection region is the area for which the null hypothesis is rejected.
- If we perform right tailed hypothesis that is the upper tail hypothesis then the rejection region lies in the right tail after the critical value.
- If we perform left tailed hypothesis that is the lower tail hypothesis then the rejection region lies in the left tail after the critical value.
Thus, for one tailed test,
Option A) One tailed test is a hypothesis test in which rejection region is in one tail of the sampling distribution
✽ Hello there! ✽
4x+9<21
Move all the constants (numbers) to the right, using the opposite operation:
4x<21-9
4x<12
Divide both sides by 4 to isolate x:
x<3
<h2>Therefore, x<3 ✔︎</h2>
Hope this helps!
~Just a felicitous girlie
#HaveASplendidDay

The value of z-score for a score that is three standard deviations above the mean is 3.
In this question,
A z-score measures exactly how many standard deviations a data point is above or below the mean. It allows us to calculate the probability of a score occurring within our normal distribution and enables us to compare two scores that are from different normal distributions.
Let x be the score
let μ be the mean and
let σ be the standard deviations
Now, x = μ + 3σ
The formula of z-score is

⇒ 
⇒ 
⇒ 
Hence we can conclude that the value of z-score for a score that is three standard deviations above the mean is 3.
Learn more about z-score here
brainly.com/question/13448290
#SPJ4