Answer:
divide 4. from 4 n 3. 3 divided by 4 answer us the answer fir x and then you times that answer to 4 and that is the answer for y
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).
Answer:
48 - 40 = $8, there is a $8 dollar increase.
Formula for change of percentage;
changed price
___________ x 100% (100/100)
original amount
Replace those values with the values we found;
40/48 x 100/100 = 20% increase.