Question

What is the average number of people that take the bus to work in New York and New Jersey?

Area | Frequency | Relative Frequency

NY | 261 | 0.75

NJ | 87 | 0.25

Build and interpret the confidence interval. Use these steps:

1. State the parameter of interest
2. Name the method
3. Verify the conditions
4. Show calculations
5. Interpret your Interval

Answer 1

The parameter of interest is the average number of people that take the bus to work.

The method used will be a two-sample proportion test.

The 95% confidence interval for the difference in the average number of people that take the bus to work in New York and New Jersey is between 0.4357 and 0.5643.

We are 95% confident that the true difference in the average number of people that take the bus to work in New York and New Jersey is between 0.4357 and 0.5643.

p1	p2	pc
0.75	0.25	0.5	p (as decimal)
261/348	87/348	348/696	p (as fraction)
261.	87.	348.	X
348	348	696	n
	0.5	difference
	0.	hypothesized difference
	0.0379	std. error
	0.4357	confidence interval 95.% lower
	0.5643	confidence interval 95.% upper
	0.0643	margin of error