01 In a random sample of 100 people in Parramatta, only 60 said "Regularly buy items from Coles". Provide an expression for 95% confidence interval for the proportion of Parramatta people who shops at Coles regularly.

Select one:

a. 0.6 1.96*(1/100)

b. 0.6 1.96

c. 0.6 1.645*((0.6*0.4)/100)

d. 0.6 1.96*((0.6*0.4)/100)

02 A random sample of 30 households was selected as part of study on electricity usage, and number of kilowatt per hours(KWH) was recorded. The average usage was found to be 375 KWH.Census was conducted for same purpose last year and it was found that the standard deviation of the usage was 81 KWH. Assuming the standard deviation is unchanged and that usage is normally distributed, provide an expression for a 99% confidence interval for the mean usage.

Select one:

a. 375 2.575 * 81/30

b. 375 2.330 * 81/30

c. 375 2.575 * 9/30

d. 375 2.752 * 81/30

03 The price of a brand jeans in a sample of 16 retailers is on average $141 with a standard deviation of 4. If this is a random sample and the prices can be assumed to be normally distributed, which of the following gives an expression for an 95% confidence interval for the average price:

Select one:

a. $141 2.131

b. $141 1.753

c. $141 1.960

d. $141 2.120

04 A 95% confidence interval for the mean number of televisions per Australian house hold is between 1.15 and 4.20.

Which of the following statement is the correct interpretation of the confidence interval given above.

Select one:

a. 95% of the samples should have its sample mean.

b. The probability that is between 1.15 and 4.20 is 0.95.

c. 95% of the Australian household have between 1.15 and 4.20 televisions.

d. We are 95% confident that the true mean number of television per Australian household is between 1.15 and 4.20

05 A survey on a random sample of 400 full-time employees in Australia gave an average weekly salary of $1530 with a standard deviation of 220.

Construct a 95% confidence interval for full-time weekly salary in Australia and write down the lower limit of the interval (up to 3 decimal places).

Hint: the upper limit is 1551.56

Answer: ?

06 A random sample of 500 males was asked if they would prefer to have a job outside the home or if they would prefer to stay at home to care for the family and home. 309 said they would prefer to have a job outside of the home.

Construct a 95% confidence interval for the proportion of males who would prefer to have a job outside of the home and write the upper limit of the interval (up to 4 decimal places).

Hints: The lower limit is 0.57541104458665

Answer: ?