In: Math
The American Bankers Association reported that, in a sample of 125 consumer purchases in France, 63 were made with cash, compared with 26 in a sample of 50 consumer purchases in the United States.
Construct a 95 percent confidence interval for the difference in proportions. (Round your intermediate value and final answers to 4 decimal places.)
The 95 percent confidence interval is from ______ to _______ .
Solution :
Given that,
= x1 / n1 = 63 / 125 = 0.504
1- = 0.496
= x2 / n2 = 26 / 50 = 0.52
1 - = 0.48
At 95% confidence level the z is ,
Z/2 = 1.96
95% confidence interval for p1 - p2 is
,
(
-
)
Z/2 *
[(1-
) / n1 +
(1 -
) / n2]
(0.504 - 0.52) 1.96 * [(0.504 * 0.496) / 125 + (0.52 * 0.48 ) / 50]
-0.180 < p1 - p2 < 0.148
(-0.180 , 0.148)
-0.180 to 0.148