Independent random samples of 100 luxury cars and 250 non-luxury cars in a certa
ID: 3262825 • Letter: I
Question
Independent random samples of 100 luxury cars and 250 non-luxury cars in a certain city are examined to see if they have bumper stickers. Of the 250 non-luxury cars, 125 have bumper stickers and of the 100 luxury car, 30 have bumper stickers. Which of the following is a 90% confidence interval for the difference in the proportion of non-luxury cars bumper stickers from the populations of cars represented by these samples? (A) (0.5 - 0.3) plusorminus 1.645 squareroot (0.5)(0.5)/250 + (0.3)(0.7)/100 (B) (0.5 - 0.3) plusorminus 1.96 squareroot (0.5)(0.5)/250 + (0.3)(0.7)/100 (C) (0.5 - 0.3) plusorminus 1.645 squareroot (155/350)(1 - 155/350)/250 + (155/350)(1 - 155/350)/100, where 125 + 30/250 + 100 = 155/350 (D) (0.5 - 0.3) plusorminus 1.96 squareroot (155/350)(1 - 155/350)/250 + (155/350)(1 - 155/350)/100, where 125 + 30/250 + 100 = 155/350 (E) (0.5 - 0.3) plusorminus 1.645 squareroot (0.4)(0.6)/250 + (0.4)(0.6)/100 A researcher has conducted a survey using a simple random sample of 50 registered voters to create a confidence interval to estimate the proportion of registered voters favoring the election of a certain candidate for mayor. Assume that the sample proportion does not change. Which of the following best describes the anticipated effect on the width of the confidence interval if the researcher were to survey a random sample of 200, rather than 50, registered voters? (A) The width of the new interval would be about 1/4 the width of the original interval. (B) The width of the new interval would be about 1/2 the width of the original interval. (C) The width of the new interval would be about the same width of the original interval. (D) The width of the new interval would be about twice the width of the original interval. (E) The width of the new interval would be about four times the width of the original interval. A 95% confidence interval for the mean reading achievement score for a population of third grade students is (44.2, 54.2). The margin of error of this interval is?. A) 95% B) 5 C) 2.5 D) 54.2 E) the answer cannot be determined from information given Refer to the previous problem. The sample mean is?. A) 44.2 B) 54.2 C) 0.9 D) 49.2 E) the answer cannot be determined from information givenExplanation / Answer
51 ) option C is correct
52)option B is correct
53)margin of error =(54.2-44.2)/2 =5
option B is correct
54)sample mean =(54.2-margin of error )=54.2-5=49.2
option D
please revert for any clarification needed.