Answer:
The critical z value used to test a null hypothesis is ±1.645.
Step-by-step explanation:
We are given that the data has a normal distribution and the number of observations is greater than fifty.
And we have to find the critical z value used to test a null hypothesis at α = 0.1 for a two-tailed test.
Firstly, as we know that to find the critical z value we need only the level of significance to be known.
Here, the level of significance is given =
= 0.10
But for the two-tailed test, the level of significance to be considered is given by =
=
= 0.05 or 5%.
Now, in the z table; we can see that the critical z value at a 5% level of significance (for the two-tailed test) is given as 1.645.
Hence, the critical z value used to test a null hypothesis at α = 0.1 for a two-tailed test is ±1.645.