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There are 6 children in a room, ages 3,4,5,6,7,8. Two more children enter the room, aged 3 and 8. Then the SD of the ages of the 8 children will be ___ than the SD of the original 6 children. A. smaller than B. larger than C. the same as The boxplots show the relationship between # cylinders a car’s engine has and the car’s fuel efficiency. True or false? Cars with a 8-cylinder engine have a lower median fuel efficiency than those with a 6-cylinder engine. A. True B. False The boxplots show the relationship between # cylinders a car’s engine has and the car’s fuel efficiency. The IQR of fuel efficiency of cars with a 4-cylinder engine is A. about 5 mpg. B. greater than 5 mpg. C. less than 5 mpg. Suppose the variance of fuel efficiency of cars with a 4-cylinder engine is 10 mpg2 (mpg = miles per gallon). If we convert the unit to km per litre (1 mpg = 0.43 km/litre), then the variance of fuel efficiency in km/litre will be … A. 10 C. B. 10×0.43 D. 10×0.432 100×0.43 The least squares regression line is the line that makes the sum of the vertical distances of the data points from the line as small as possible. True or false? A.True B.False There are 2 midterms in STAT 100. Here are some summary statistics of the midterm grades: Midterm 1: SD=5 , Midterm 2: SD=10 Correlation between the scores of the two midterms = 0.80. Mary is taking STAT 100. Her first midterm grade is 15 points above the mean midterm 1 grade. What will you predict her midterm 2 grade to be? A. B. C. D. 24 points above the mean midterm 2 grade. 30 points above the mean midterm 2 grade. The mean midterm 2 grade. There is insufficient information to answer the question. You flip two coins. Event A = the first flip gives a head Event B = the second flip gives a tail The two events are … A. B. C. D. E. complementary. disjoint. independent. both (A) and (C). both (B) and (C). Ignoring multiple births, assume babies born at a hospital are independent with the probability that a baby is a boy and the probability that a baby is a girl is both equal to ½. The probability that the next two babies born are of the opposite sex is: 1/8 B. 1/6 C. 1/4 D. 1/2 A. Consider two independent random variables X and Y. Given that Var(X)=10 and Var(Y)=4. Then Var(X – Y) equals to 4 B. 6 C. 10 D. 14 A. A die is rolled five times. Let X be the number of 6’s observed. Then: X is not Binomially distributed. B. X ~ Bin(6, 1/2) C. X ~ Bin(6, 1/6) D. X ~ Bin(5, 1/6) A. The lifetime of electric bulbs has mean 440 hours with standard deviation 400 hours. So the lifetime is not normally distributed. The sample mean of a simple random sample of 2 light bulbs: Will be approximately normally distributed by the Central Limit Theorem B. Will be approximately normally distributed by the Law of Large Numbers C. Will not be approximately normally distributed. A. The lifetime of electric bulbs has mean 440 hours, with standard deviation 400 hours. The lifetime is not normally distributed. The distribution of the lifetimes of a simple random sample of 100 light bulbs: Will be approximately normally distributed by the Central Limit Theorem. B. Will be approximately normally distributed by the Law of Large Numbers. C. Will not be approximately normally distributed. A. For a random sample of size 100 of the bulbs from the previous problem, there is a 68% chance that the sample mean is within _____ hours of 440 hours. 4 B. 40 C. 400 A. The standard deviation of heights of 24-month old Canadian females is 4 cm. I take a SRS of 100 of these females and find that my sample mean is 86.1 cm. A 68% confidence interval for the mean height of all 24-month old Canadian females: is 86.1 ± 0.4 cm. B. is 86.1 ± 4 cm. C. cannot be calculated as the SRS is biased. A. A simple random sample of 100 36-month old Canadian females yielded a 68% confidence interval for the mean height of all 36-month Canadian females: (80.1 cm, 80.9 cm). Then: 68% of all 36-month old Canadian females had heights in the interval (80.1cm, 80.9cm) B. 68% of the females in the sample had heights in the interval (80.1cm, 80.9cm) C. There is a 68% chance that the mean height of all 36month old Canadian females is in the interval (80.1cm, 80.9cm). D. None of the above. A. Suppose that under the null hypothesis, our test statistics Z has a N(0,1) distribution, with large values of Z favouring the alternative hypothesis. We observe z = 0.2. Then, The p-value is 0.20 B. The p-value is less than 0.20 C. The null hypothesis is plausible, since z=0.2 is not unusual. A. The reading comprehension test scores for fourth graders are believed to follow the normal distribution. Fifteen randomly selected fourth graders took the test, and their scores gave a mean of 73 and an SD of 8. The English teacher wants to construct a confidence interval for the mean test score based on the sample of 15 fourth graders. What distribution will she used to find the critical point? The standard normal distribution. B. The t-distribution with 14 degrees of freedom. C. The t-distribution with 15 degrees of freedom. D. None of the above is appropriate as the sample size 15 is not large enough. A. Is the mean age of married men greater than the mean age of married women? You randomly sample 10 married couples. The ages of the 10 husbands and their wives are recorded. You then carry out a hypothesis test to answer the above question. Which of the following hypothesis tests is the most appropriate? A. B. C. D. The paired t-test (1-sided) The paired t-test (2-sided) The 2-sample t-test (1-sided) The 2-sample t-test (2-sided) In a comparison of gas mileage, measurements were taken on 10 Honda Civics, 15 Toyota Yaris’ and 30 Mazda 3’s. To test that the mean gas mileages of the three car types are the same, we would need an F distribution with numerator degrees of freedom = 2 and denominator degrees of freedom = ? (ie, the distribution is F2,a , what is our value of a?) A. B. C. D. 3 52 54 55