Answer:
The sample does not contradicts the manufacturer's claim.
Step-by-step explanation:
We are given the following in the question:
Population mean, μ = 200 mg
Sample mean, 
= 211.5 mg
Sample size, n = 20
Alpha, α = 0.05
Sample standard deviation, s = 18.5 mg
a) First, we design the null and the alternate hypothesis for a two tailed test
We use Two-tailed t test to perform this hypothesis.
b) Formula:
Putting all the values, we have
c) Now,
Since, the calculated t-statistic does not lie in the range of the acceptance region(-2.0930,2.0930), we reject the null hypothesis.
Thus, the sample does not contradicts the manufacturer's claim.
d) P-value = 0.011934
Since the p-value is less than the significance level, we reject the null hypothesis and accept the alternate hypothesis.
Yes, both approach the critical value and the p-value approach gave the same results.
