do we have to choose between the two in exam? will we be given both? or individual question will give us what is required?

i assume we will have to determine by sample size and known/unkown variance

It’s up to you to determine whether to use a z-table or a t-table. They’ll give you t-tables and, for unusual values, z-tables, but you have to decide which to use.

ok thx…

We will decide between z and t test by seeing the sample size and see if the population variance is given or not .