Quiz 1 (4 points per question; maximum
score 40 points for Quiz 1)

1. A random sample is one ______

a.That is haphazard

b.That is unplanned

c.In which every unit of a particular
size has an equal probability of being selected

d.That ensures that there will be no
uncertainty in the conclusions

1. Stratified sampling___

a.Can be more representative than
simple randomized sampling

b.Can be used if the population has a
number of distinct groups

c.Is done by randomly sampling from
subgroups in a way that is proportional to their size in the population

d.All of the above

1. In an experiment on the effect of exercise on memory,
   the independent variable is __(choose only one answer)

a.Number of hours of exercise

b.Recall score on a memory test

c.Gender of the subjects

d.Gender of the experimenter

1. For the scores 3, 5, 8, 10, 14, 17, 21, 25, calculate
   the 75thpercentile using the following formula: R
   = P/100 x (N + 1)

a. 6.75

b. 17

c. 21

d. 20

1. The area under the curve of a probability distribution
   is _____

a. 0

b. 100

c. .68

d. 1

1. .5pt;=”” “arial”,”sans-serif”;=””>Sometimes we need to use
   median instead of mean to better measure central tendency in a sample if

a. The sample has a large variance

b. The distribution is extremely
right-skewed

c. We have measurement error when
collecting the sample

d. The sample mean is too small

1. .5pt;=”” “arial”,”sans-serif”;=””>In a bell-shaped
   distribution, changing ___can make the distribution flatter (i.e. more
   compressed); and changing ___ can shift the distribution to the left or to
   the right.

a. Variance, mean

b. Mean, variance

c. Range, standard deviation

d. Mode, range

e. Mean, range

f. Mode, variance

1. .5pt;=”” “arial”,”sans-serif”;=””>If a distribution is
   left-skewed, its mean is usually___ its median

a. bigger than

b. smaller than

c. equal to

d. we can not know

researcher collected BMI
(Body Mass Index) of 50 students in an Engineering school. He found the mean
BMI was much smaller than the median BMI. The reason for this might be___

a.Several students had much smaller BMI scores than the other
students

b.Several students had much larger BMI scores than the rest

c.The researcher made some measurement errors

d.All the students had smaller BMI scores, compared to national
average

1. .5pt;=”” “arial”,”sans-serif”;=””>In a bell-shaped distribution, ___can determine whether
   the distribution is flatter (i.e. more compressed); and ___ can determine
   the distribution location

a.Variance, mean

b.Mean, variance

c.Range, standard deviation

d.Mode, range

e.Mean, range

f.Mode, variance

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