Question

For a 3.3 volt Zener diode, the average surge current is 1.265 amps with a standard deviation of .21 amps. Vishay Electronics believes they have improved the diode and which allows it to resist an even higher surge current. They tested 48 3.3 volt Zener diodes they created with their procedure and found an average surge current of 1372 amps. At a significance level of 0.01, does the new Zener diode have a higher average surge current?

Answer 1

Below are the null and alternative Hypothesis,
Null Hypothesis, H0: μ = 1.265
Alternative Hypothesis, Ha: μ > 1.265

Rejection Region
This is right tailed test, for α = 0.01
Critical value of z is 2.326.
Hence reject H0 if z > 2.326

Test statistic,
z = (xbar - mu)/(sigma/sqrt(n))
z = (1.372 - 1.265)/(0.21/sqrt(48))
z = 3.53

P-value Approach
P-value = 0.0002
As P-value < 0.01, reject the null hypothesis.

yes, the new Zener diode has a higher average surge current