hello everyone,,

i am a little confuse and need help with my data ,,,

1- i want to apply z test for mean different between two kind of funds,, my data have 139 observations,, and i don't know what option should i choose for z test ,, my teacher said that spss automatically transform t test to z test if data more than 30 ,, is it true ?

2- i need to test for one tail but spss dont have option for that ,,, how can do z test for mean different for one tail?

i will appreciate your help

thank you