Suppose that a poll taken 10 years ago found that 68% of parents spank their chi

Question

Suppose that a poll taken 10 years ago found that 68% of parents spank their children. Suppose a recent poll of 350 adults with children finds that 213 indicated that they spank their children. Complete parts (a) and (b) below (a) Assuming parents' attitude toward spanking has not changed since the original pol, how many of the 350 parents surveyed would be expected to spank their children? The expected amount of parents surveyed that would spank their children is (Round to the nearest whole number as needed.) (b) Do the results of the survey suggest that parents' attitude toward spanking may have changed since the original poll? Why? 0 A. 0 B. ° C. 0 D. No, 213 is within one standard deviation of the expected amount of adults that spank their children. No. 213 is inside the "usual" observation interval of this survey. Yes, 213 is outside the "usual" observation interval of this survey. Yes, 213 is less than the expected amount of adults that spank their children.

Explanation / Answer

WE will solve the problem using the patams of the distribution:

p0 (Spank) = .68
n = 350
x = 213
p0 = x/n = 213/350 = .61

a. E(X) = np0 = 350*.68 = 238

b. Stdev= sqrt(npq) = sqrt(.681*.320*350) = 8.733

THe Z = (213-238)/8.733 = -2.86
Since Z>2 in magnitude we conclude that the event is unusual and therefore answer is C: Yes, 213 is outside the 'usual' observation interval of this survey

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