In an article in the Journal of Advertising, Weinbergerand Spotts compare the use of humor in television ads in the UnitedStates and in the United Kingdom. Suppose that independent randomsamples of television ads are taken in the two countries. A randomsample of 400 television ads in the United Kingdom reveals that 145use humor, while a random sample of 500 television ads in theUnited States reveals that 124 use humor.

(a) Set up the null and alternative hypothesesneeded to determine whether the proportion of ads using humor inthe United Kingdom differs from the proportion of ads using humorin the United States.

H₀: p₁ −p₂ (Click to select)≠= 0 versusH_a: p₁ −p₂ (Click to select)=≠ 0.

(b) Test the hypotheses you set up in part a byusing critical values and by setting α equal to .10, .05, .01, and.001. How much evidence is there that the proportions of U.K. andU.S. ads using humor are different? (Round the proportionvalues to 3 decimal places. Round your answer to 2 decimalplaces.)

  z          

(Click to select)RejectDo not Reject H₀ ateach value of α; (Click to select)very strongstrongextremelystrongsomenone evidence.

(c) Set up the hypotheses needed to attempt toestablish that the difference between the proportions of U.K. andU.S. ads using humor is more than .05 (five percentage points).Test these hypotheses by using a p-value and by setting αequal to .10, .05, .01, and .001. How much evidence is there thatthe difference between the proportions exceeds .05? (Roundthe proportion values to 3 decimal places. Round your z value to 2decimal places and p-value to 4 decimalplaces.)

z
p-value

(Click to select)RejectDo not Reject H₀ ateach value of α = .10 and α = .05; (Click to select)verystrongstrongextremely strongsomenone evidence.

(d) Calculate a 95 percent confidence intervalfor the difference between the proportion of U.K. ads using humorand the proportion of U.S. ads using humor. Interpret thisinterval. Can we be 95 percent confident that the proportion ofU.K. ads using humor is greater than the proportion of U.S. adsusing humor? (Round the proportion values to 3 decimalplaces. Round your answers to 4 decimal places.)

95% of Confidence Interval                     [, ]

(Click to select)NoYes the entire interval is above zero.