Suppose a student takes a standardized test measuring college level skills. Scor

Question

Suppose a student takes a standardized test measuring college level skills. Scores on the test are normally distributed with a mean of 500 and a standard deviation of 100. The student obtains a z score of 0 (zero) on the test. Which of the following statements is true of this person's score? a. The student received a score of zero on the test. b. The student's score is above the mean of 500. c. The student's score is below the mean of 500. d. The student scored 500 on the test. If each of a set of raw scores is transformed into a Z-score, the new distribution will have a standard deviation equal to a. zero. b. one. c. the mean of the original distribution. d. the standard deviation of the original distribution. e. a variable, depending upon the shape and spread of the original distribution. What percentage of scores, approximately, lies between the mean and - 1 standard deviation for a normal distribution with a mean of 100 and a standard deviation of 15? a. 15.00% b -15.00% c. 34.00% d. -34.00% Suppose that a normal model describes the acidity (pH) of rainwater, and that water tested after last week's storm had a z-score of 1.8. This means that the acidity of the rain a. had a pH 1.8 higher than average rainfall. b. had a pH of 1.8. c. varied with standard deviation 1.8 d. had a pH 1.8 standard deviations higher than that of average rainwater. e. had a pH 1.8 times that of average rainwater. To estimate the number of words defined in the Merriam-Webster Dictionary, Bill randomly selected 20 different pages and then counted the number of words defined on each page. Identify which type of sampling he used. a. systematic b. stratified c. random d. cluster In a multi-campus university, there are 20 lab sections of a statistics class. The University decides that a student evaluation needs to be administered. It decides at first to randomly select 7 of the 20 lab sections and then administer the evaluation of the students in those sections. a. Convenience sampling. b. Cluster sampling. c. Simple random sampling. d. Stratified random sampling.

Explanation / Answer

7) z- score = 0 means X is equal to population mean
Which is 500
Hence option d) the student scored 500 on the test is correct

8) if the data is transformed into z-score , then sd = 1
As it will become standard normal .
Option b) one is correct

9)
Between mean and -1 sd ,the percentage is always 34 .
Remember 68-95-99.7 rule
10) z = 1.8
This means pH is 1.8 sd higher than average water
Option d) is correct

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