Question

A researcher wishes to assess how much the inclusion of a refrigerator magnet affects the response rate to direct mail for a local real estate agency. Of the 1058 mailings with a magnet, 15 homeowners contacted the agency. Of the 2600 mailings without a magnet, 25 homeowners contacted the agency. For a 95% confidence level, what is the MARGIN OF ERROR (ME) for the difference in the response rates? (Answer as a rate, not a percent. Record your answer accurate to at least the nearest THIRD decimal place with standard rounding.)

Answer 1

i am denoting mailing with magnet as A and mailing without magnet as B.

sample size for A =

sample size for B =

z critical value for 95% confidence level = 1.960

the margin of error for a 95% confidence level, for the difference in the response rates (with magnet - without magnet) :-

= 0.008

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