Hello, I have the following question;

Problem 10. Telephone lines

A cell company claims that at least 15% of its customers have 2 or more lines. The company selects a random sample of 500 customers and finds that 65 have 2 or more telephone lines. If = 0.02, show all key steps and test whether the proportion is less than 15% using the critical value approach. [10 marks]

I can't help but feel like I might have missed something in trying to answer this question.

My final result was z=-3.20

(using an area of significance 2.334)