practice1

# practice1 - Practice 1 for Mid-Term Exam Please Note:...

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Practice 1 for Mid-Term Exam Please Note: Questions 15 and 33 are about the central limit theorem which we will study after the midterm. So you are not responsible for these two questions for the midterm. 1. You can tell if a dataset is right-skewed by looking at a) the sample variance b) the scatterplot c) the correlation coefficient d) the boxplot 2. Which of the following makes it easy to compare center and spread of samples from several different populations graphically ? a) Scatterplots b) Boxplots c) Histograms d) digidot plot 3. Which of the following is always true? (for a normal distribution) a) At least 95% of the data are within 2 standard deviations of the mean b) The distribution of a random variable is always bell-shaped c) At least 75% of the data are within one standard deviation of the mean d) Histogram is constructed based on variance and mean 4. For a continuous population, the probability that an observation is smaller than the median is a) 0.5 b) 0.75 c) 1.0 d) Dependent on the distribution 5. Suppose you are playing the following game: You toss a fair coin, and win \$3 if you get a head and lose \$2 if you get a tail. The expected value of this game is thus 50 cents. This means a) You will win 50 cents if you play the game enough times b) You have 50% chance of winning 50 cents c) Your probability of winning is greater than 50% d) On the average you win about 50 cents per game, if you play enough times 6. The event A and its complement A’ are a) always independent b) always mutually exclusive c) equally likely

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d) none of the above 7. Which of the following is not a statistic? a) the sample size b) the sample mean c) the sample maximum d) the sample variance 8. Suppose I randomly pick 12 persons from this class and ask them how many compact discs each of them owns. a) The mean number must be an integer since the measurements are all integers b) The sample is normally distributed c) The sample mode must be an integer since the measurements are all integers d) The median number must be an integer since the measurements are all integers. 9. If P(A/B) is equal to P(A) then: a) A and B are independent b) A and B are mutually exclusive c) A and B have the same probability d) none of the above 10. Tom’s score on the first mid-term has the Z -score (standard score) of -2.0 a) There are approximately 2.5% of the people who did worse than Tom b) Tom’s score is two IQR’s below the median c) Tom’s score is two standard deviations below the mean
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## This note was uploaded on 10/08/2010 for the course CHE 220 taught by Professor Elkamel during the Spring '10 term at Waterloo.

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practice1 - Practice 1 for Mid-Term Exam Please Note:...

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