Question

I have the question and the answer, but I can't figure out how to get the answer.

​

Answer 1

See below.

Explanation:

`z = (15 - 12)/((2.8)/(√(20)))`

`z = (3)/((2.8)/(√(4 * 5)))`

`z = (3)/((2.8)/(2√(5)))`

`z = 3 * (2√(5))/(2.8)`

`z = (6 √(5))/(2.8)`

`z = (13.416)/(2.8)`

`z = 4.792`