I know that the answer to the question is +2.23. I am struggling to remember the steps to get to the answer. The image is to big to uploa so I will type it out. It is widely believed that 38% of all...

I know that the answer to the question is  +2.23. I am struggling to remember the steps to get to the answer. The image is to big to uploa so I will type it out.

It is widely believed that 38% of all students have a part-time job. You feel it’s more than that. You take a sample of 325 students from the population and find that 143 of those students are working part-time.

What is the standard score for the obtained proportion?