A sample of 1700 computer chips revealed that 73% of the chips do not fail in the first 1000 hours of their use. The company's promotional literature claimed that more than 70% do not fail in the first 1000 hours of their use. Is there sufficient evidence at the 0.05 level to support the company's claim?

Solution :

It is a left tailed test.

Given : n = 1700

α = 0.05

We want to test,

the null hypothesis,  

the alternate hypothesis,

Test statistics is

Thus z - critical value = 1.64

Since, z calculated  -----  z-critical value

             (2.70)                          (1.64)

Thus we reject the null hypothesis.

So there is sufficient evidence at 0.05 level to support the company's claim that more the 70% do not fail in the first 1000 hours of their use.

the answer is simply just 6n add the two together as they have an n