Question

(20.08) With over 50% of adults spending more than an hour a day on the Internet, the number experiencing computer- or Internet-based crime continues to rise. A survey in 2010 of a random sample of 1034 adults, aged 18 and older, reached by random digit dialing found 125 adults in the sample who said that they or a household member was a victim of a computer or Internet crime on their home computer in the past year.

Answer 1

the hint and formulas are below the question but im not getting any of the options... and i have 6 minutes to turn it in =/

Answer 2

ok i'll see what I can do

Answer 3

thanks

Answer 4

the 96% CI I'm getting is

( 0.100, 0.142 )

Answer 5

using the plus four method, I'm getting

( 0.101, 0.143)

Answer 6

They were correct :) ok, now that im not all in a rush, how did you get them?

Answer 7

for the first part

p-hat = X/N = 125/1034 = 0.120889748549323

Answer 8

for the 96% confidence interval, the z critical value is roughly z = 2.05374891063182

this is the value of k such that P( -k < Z < k ) = 0.96

Answer 9

now we have enough info to compute the lower and upper bounds of the confidence interval

Answer 10

Lower Bound of Confidence Interval


L = phat - z*sqrt( (phat(1-phat))/n )

L = 0.120889748549323 - 2.05374891063182*sqrt( (0.120889748549323(1-0.120889748549323))/1034 )

L = 0.100068657367993

L = 0.100

Answer 11

ok..

Answer 12

Upper Bound of Confidence Interval


U = phat + z*sqrt( (phat(1-phat))/n )

U = 0.120889748549323 + 2.05374891063182*sqrt( (0.120889748549323(1-0.120889748549323))/1034 )

U = 0.141710839730653

U = 0.142

Answer 13

so the 96% CI is (L,U) = ( 0.100, 0.142 )

Answer 14

the 96% CI for the plus four method will be calculated the exact same way..but...


phat = (X+2)/(N+4)

phat = (125+2)/(1034+4)

phat = 0.1223506743738

Answer 15

make sense?

Answer 16

Yes, it all makes perfect sense, thanks!

Answer 17

ok great