Answer: It costs $5.52 to Sam to buy 12 stamps.
Step-by-step explanation:
Given: Sam paid $8.28 for 18 stamps.
Thus, the cost of 18 stamps = $8.28
Then the cost of 1 stamp=
Thus, the cost of 1 stamp=$0.46
With the same rate , the cost of 12 stamps=
Therefore, the cost of 12 stamps= $5.52
hence, it costs $5.52 to Sam to buy 12 stamps.
Answer:
The 95% confidence interval for the proportion of students who get coaching on the SAT is (0.1232, 0.147).
Step-by-step explanation:
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 z-score that has a p-value of .
427 had paid for coaching courses and the remaining 2733 had not.
This means that
95% confidence level
So , z is the value of Z that has a p-value of
, so
.
The lower limit of this interval is:
The upper limit of this interval is:
The 95% confidence interval for the proportion of students who get coaching on the SAT is (0.1232, 0.147).