We have a random sample of 200 something

with a sample average = 21

and standard deviation = 10

Can we say that the population average is greater then 14?

If we test with a signifance level = 0.01 then what value has the test statistics?

This is my thinking, because we have n>30, then we have to use the z - test?

I am calculating the value of test statistics for about 1 hour and still it's incorrect!