Question

1. The target thickness for silicon wafers used in a type of integrated circuit is 200 mm. A sample of 16 wafers is obtained and the thickness of each one is determined, resulting in a sample mean thickness of 220 mm and a sample standard deviation of 5 mm. Does this data suggest that true average wafer thickness is something other than the target value?

Answer 1

Answer)

As the population standard deviation is unknown, we will use t test

Null hypothesis Ho : u = 200

Alternate hypothesis Ha : u is not equal to 200

Test statistics t = (sample mean - claimed mean)/(s.d/√n)

Sample mean = 220

Calimed mean = 200

S.d = 5

N = 16

t = (220-200)/(5/√16)

t = 16

Degrees of freedom is = sample size -1, 15

For df 15 and test statistics 16, P-value from t distribution is = <0.0001

As the P-Value is extremely small

We reject the null hypothesis

And we do have enough evidence to support the claim that the average thickness is other than the target value