Many people have trouble setting up all the features of their smartphones, so a company has developed what it hopes will be easier instructions. The goal is to have at least 96% of customers succeed. The company tests the new system on 200 people, of whom 188 were successful. Is this strong evidence that the new system fails to meet the company's goal? A student's test of this hypothesis is shown. How many mistakes can you find?
H0: p̂ = 0.96
HA: p̂ ≠ 0.96
SRS, 0.96 (200) > 10
188/200 = 0.94; SD(p̂) = √(0.94)(0.06) / 200 = 0.017
z = 0.96 - 0.94 / 0.017 = 1.18
P = P(z > 1.18) = 0.12
There is strong evidence the new instructions don't work.