math i need help asap

Question

More and more people are abandoning national brand products and buying store brand products to save money. The president of a company that produces national brand coffee claims that 40% of the people prefer to buy the national brand coffee. A random sample of 700 people who buy coffee showed that 259 of them buy national brand coffee. Using α = 0.01, can you conclude that the percentage of people who buy coffee is different from 40%?                                                                                          

Answer 1

Ho: p = 0.40

Ha: p != 0.40

sample proportion (phat) = 259/700 = 0.37

sample size(n) = 700

compute z = (phat - p)/sqrt(p * (1-p)/n) = (0.37 - 0.4)/sqrt(0.4 * 0.6/700) = -1.62

critical values for alpha = 0.01 and a two-sided test are -2.575 and 2.575

since z is not outside the range of critical values, Ho is not rejected and we cannot conclude the percentage is different from 40.