Q1) To give 98% confidence interval for population mean μ, you would use critical value

Choose one answer.

a) 1.960

b) 2.326

c) 2.054

d) 2.575

Q2) Opinion poll says that result of their latest sample has margin of error of plus or minus three percentage points. This means that

Select one answer.

a) We could be certain that poll result is within three percentage points of the truth if there were no non response

b) The poll used method which gives a result within 3 percentage points of truth in 95% of all samples

c) we can be certain that poll result is within 3 percentage points of the truth about the population

Q3) A laboratory scale is known to have standard deviation of σ = 0.001 gram in repeated weightings. Scale readings in repeated weightings are Normally distributed, with mean equal to true weight of the specimen. If you weigh specimen three times on this scale, mean result  has standard deviation

Choose one answer.

a) 0.000577 gram

b) 0.003 gram

c) 0.001 gram

d) 0.000333 gram

Q4) Government report says that 90% confidence interval for mean income of American households is $59,067 ± $356. This is based on random sample of 60,000 households. If same sample results had come from sample of 15,000 households, new margin of error would be

Select one answer.

a) ± 356          

b) ± 712          

c)  ± 68            

d) ± 178          

Q5) Gallup Poll asked 1060 randomly chosen adults, "How would you rate overall quality of the environment in this country today-as excellent, good, only fair, or poor?" In all, 46% of the sample rated environment as good or excellent. Gallup said that "one can say with 95% confidence that margin of sampling error is ± 3 percentage points." If poll had interviewed 1500 persons rather than 1060, margin of error for 95% confidence would be

Select one answer.

a) Greater than ±3 percentage points

b) Cannot be determined as futher information is needed.

c) less than ±3 percentage points

d) ±3 percentage points