Answer:
a
The null hypothesis is 
The alternative hypothesis is 
The null hypothesis is rejected
b
The 99% confidence level is 
Step-by-step explanation:
From the question we are told that
The sample size is n = 10
The population mean is 
The level of significance is 
The sample data is
13.3987, 13.3957, 13.3902, 13.4015, 13.4001, 13.3918, 13.3965, 13.3925, 13.3946, and 13.4002
Generally the sample mean is mathematically represented as

=> 
Generally the sample standard deviation is mathematically represented as

=> 
=> 
The null hypothesis is 
The alternative hypothesis is 
Generally the test statistics is mathematically represented as

=> 
=> 
Generally the p-value is mathematically represented as

From the z-table 
So


So from the obtained value we see that

Hence the null hypothesis is rejected
Consider the b question
Given that the confidence level is 99% then the level of significance is

=>
Generally from the normal distribution table critical value of
is

Generally the margin of error is mathematically represented as

=> 
=> 
Generally the 99% confidence interval is mathematically represented as

=> 