Question

Stats help please
An article regarding interracial dating and marriage recently appeared in a newspaper. Of the 1702 randomly selected adults, 301 identified themselves as Latinos, 324 identified themselves as blacks, 253 identified themselves as Asians, and 776 identified themselves as whites. In this survey, 86% of blacks said that their families would welcome a white person into their families.
State the confidence interval.

Answer 1

Confidence interval is calculated by adding and subtracting the margin of error to the proportion given in the problem.

Answer 2

Yeah, but I can't find the margin of error either.

Answer 3

What is alpha in this case?

Answer 4

.1

Answer 5

No, .05

Answer 6

You want a 90% confidence level? I didn't see that stated in the problem.

Answer 7

No..95% I was being silly.

Answer 8

Oh I forgot to include, it wants a 95% confidence interval.

Answer 9

Construct a 95% confidence interval for the population proportion of blacks that would welcome a white person into their family.

Answer 10

okay..so 1-.95 is .05. and that makes alpha/2 .025. What z value is that associated with?

Answer 11

Um...I'm not sure.

Answer 12

Look in the body of your Z table for .025.

Answer 13

You want the z-score whose area is .025

Answer 14

But for this homework, there's no z table included and I'm not sure if we can have one for the test. We do however have a calculator.

Answer 15

What calculator are you using?

Answer 16

ti-84

Answer 17

not sure how to do this with a ti-84

Answer 18

um...i looked it up and it says We can find -z by using TI-83 or TI-84 calculator invNorm function. so 2nd.Vars.3.invNorm.

Answer 19

but i'm not sure where to go from that.

Answer 20

Go to STAT, Tests, 1-prop Z-interval and put in the values

Answer 21

What values would I put? I tried putting in 200.66 for x, 254 for n and C-level as 95 and got a domain error.

Answer 22

x is 324, n is 1702 and C-level is 95

Answer 23

But isn't that not right? Isn't it asking for 95% confidence interval for the population proportion of blacks that would welcome a white person into their family instead of about the total population?

Answer 24

It's a random sample of 1702 people.

Answer 25

Ok so I got the answer right. You were supposed to do .86 times 324 to get the number of black people who answered yes.