A College Alumni Fund Appeals for Donations by Phoning or Emailing

question 63

Multiple Choice

A college alumni fund appeals for donations by phoning or emailing recent graduates. A random sample of 300 alumni shows that 40% of the 150 who were contacted by telephone actually made contributions compared to only 30% of the 150 who received email requests. Which formula calculates the 98% confidence interval for the difference in the proportions of alumni who may make donations if contacted by phone or by email?

• A) \( (0.40-0.30)+7.33 \sqrt{\frac{(0.40)(0.60)}{300}+\frac{(0.30)(0.70)}{300}} \)
• B) \( (0.40-0.30) \pm 2.33 \sqrt{\frac{(0.35)(0.65)}{300}} \)
• C) \( (0.40-0.30) \pm 2.33 \sqrt{\frac{(0.35)(0.65)}{150}} \)
• D) \( 0.40-0.30)+7.33 \sqrt{\frac{(0.40)(0.60)}{150}+\frac{(0.30)(0.70)}{150}} \)
• E) \( (0.40-0.30)+2.33 \sqrt{\frac{(0.35)(0.65)}{150}+\frac{(0.35)(0.65)}{150}} \)