In an investigation into ownership of laptops among school students, 200 randomly chosen studens were interviewed.It is found that 140 of them owned a laptop.

(a) Find the 99% confidence interval for the proportion of all school students owning a laptop.

(5 marks)

(b) Test, at 5% level of significance, whether the proportion of school students owning a laptop is less than 75%.

(8 marks)