In a class there are 20 boys and 15 girls.The ratio of boys to girls is
2 answers:
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Answer:
First question: LCL = 522, UCL = 1000.5
Second question: A sample size no smaller than 418 is needed.
Step-by-step explanation:
First question:
Lower bound:
0.36 of 1450. So
0.36*1450 = 522
Upper bound:
0.69 of 1450. So
0.69*1450 = 1000.5
LCL = 522, UCL = 1000.5
Second question:
In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of
, we have the following confidence interval of proportions.
In which
z is the zscore that has a pvalue of .
The margin of error is:
The project manager believes that p will turn out to be approximately 0.11.
This means that
95% confidence level
So , z is the value of Z that has a pvalue of
, so
.
The project manager wants to estimate the proportion to within 0.03
This means that the sample size needed is given by n, and n is found when M = 0.03. So
Rounding up
A sample size no smaller than 418 is needed.