Question

Assume the null hypothesis states that the mean is at least $18$. Is this a left-tailed, right-tailed, or two-tailed test?

Short answer

It is a left-tailed test if the null hypothesis states that the mean is at least$18$

Step-by-step solution

Introduction

The rejection zone in left-tailed test is at the extreme left of the distribution. The null hypothesis in this case is that the claimed value is less than or equal to the population mean value.

Explanation

According to the null hypothesis, the mean must be at least $18$. The null hypothesis states that the mean should be at least $18$

the code for this is:

$H_0:\mu \ge 18$

The alternative hypothesis to the null hypothesis is as follows:

$H_a:\mu <18$

The alternative hypothesis's sign is in this case. As a result, this is a left-tail test.