Answer:
Question 1
The correct option is A
Question two
The correct option is B
Question three
Question four

Question five
The correct option is A
Step-by-step explanation:
The population mean is 
The sample size is n = 16
The population size is N = 4000
The sample mean is 
The standard deviation is 
Considering the first question
The correct option is A
z test because the SD of the population is known and the weights follow the normal curve
Considering the second question
The correct option is B
Yes, because with only 20 observations the sample SD is not a great estimate of the true population SD.
Considering the third question
Generally the standard error 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 the

=> 
From the obtained values we see that

So we reject the null hypotheses
The conclusion
it's very unlikely that the factory is making the candy bars 50 grams as they claim