Question

What proportion of all Americans believe the president is doing a good job? A recent poll found that 39% of 1000 randomly selected Americans approved of the way George W. Bush is handling his job as president.

a) Does this mean that only 39% of all Americans approve of the way George W. Bush is handling his job as president?
b) For a sample proportion, as long as the population is greater than ten times the sample size, we can approximate the standard deviation to be the square root of p times 1 minus p divided by n What is the standard deviation for this sample?

Answer 1

c) What is the critical value for a 90% confidence interval?
d) What is the critical value for a 95% confidence interval?
e) What is the 90% confidence interval? Be sure to include the formula with your numbers plugged in. Use the model: p plus or minus z times the square root of p times 1 minus p divided by n
f) What is the 95% confidence interval?

Answer 2

@jim_thompson5910

Answer 3

A @schmidtdancer

Answer 4

@jim_thompson5910

Answer 5

What do you think it is? @schmidtdancer

Answer 6

im not sure.

Answer 7

@jim_thompson5910 ? how do i start with a

Answer 8

Ok

Answer 9

you have a SRS of 1000 people

There are about 300 million people in this country. Even if you exclude young children who can't vote, that's still a lot of people.

Answer 10

ok

Answer 11

I got no, this 39 percent refers to the 1000 Americans sampled.

Answer 12

so do you think a SRS of 1000 people could represent a population of 300 million accurately?

Answer 13

what about b? i got:(b) sqrt np(1-p)
= sqrt(1000(0.39)0.61)
= 237.9 <----

Answer 14

?

Answer 15

use sqrt(p(1-p)/n)

Answer 16

so is that b?

Answer 17

that's part of b, yes

Answer 18

is b the answer i had..?

Answer 19

237.9

Answer 20

is c: (0.3646 , 0.4154)

Answer 21

s = sqrt(p(1-p)/n)

s = sqrt(0.39(1-0.39)/1000)

s = ???

Answer 22

s=0.01542400726

Answer 23

better

Answer 24

so b is: s = sqrt(0.39(1-0.39)/1000)
s= 0.01542400726

Answer 25

whats c? i got (0.3646 , 0.4154)

Answer 26

is b and c right^^

Answer 27

yes b is s = sqrt(0.39(1-0.39)/1000)
s= 0.01542400726

Answer 28

ok!

Answer 29

c?

Answer 30

c) and d) are found using that wolfram alpha calculator we used before

Answer 31

ok is what i have right tho

Answer 32

remember how we got 1.645 and 1.96 ?

Answer 33

yea

Answer 34

?

Answer 35

well those are the critical values for the 90% and the 95% confidence intervals

Answer 36

ok

Answer 37

how do i find c with it

Answer 38

just something you'll have to look up in a table or use a calc (or memorize)

Answer 39

those are the answers to C and D because that's all those parts want

Answer 40

Oh ok. so c is 1.645

Answer 41

d is 1.96?

Answer 42

(e) (0.3646,0.4154)

(f) (0.3598 , 0.4202) are these right

Answer 43

yep you got c and d correct

Answer 44

hold on while i check e and f

Answer 45

kk

Answer 46

you nailed both e and f, congrats

Answer 47

yay! thanks!

Answer 48

yw