When Scholastic Achievement Test scores (SATs) are sent to test-takers, the percentiles
associated with scores are also given.
Suppose a test-taker scored at the 87th percentile on the
verbal part of the test and at the 14th percentile on the quantitative part. Interpret these results.
A) This student performed better than 13 of the other test-takers on the verbal part and
better than 14 on the quantitative part.
B) This student performed better than 87 of the other test-takers on the verbal part and
better than 86 on the quantitative part.
C) This student performed better than 13 of the other test-takers on the verbal part and
better than 86 on the quantitative part.
D) This student performed better than 87 of the other test-takers on the verbal part and
better than 14 on the quantitative part.
Q. 2The university police department must write, on average, five tickets per day to keep
department revenues at budgeted levels. Suppose the number of tickets written per day follows
a Poisson distribution with a mean of 7.5 .
Find the probability that fewer than six tickets are
written on a randomly selected day.
A) 0.758564 B) 0.621845 C) 0.241436 D) 0.378155
Q. 3If a sample has mean 0 and standard deviation 1, then for every measurement x in the sample
the z-score of x is x itself.
A) True B) False
Q. 4Suppose the number of babies born each hour at a hospital follows a Poisson distribution with a
mean of 3. Some people believe that the presence of a full moon increases the number of births
that take place.
Suppose during the presence of a full moon, the hospital experienced eight
consecutive hours with more than four births each hour. Based on this fact, comment on the
belief that the full moon increases the number of births.
A) The belief is supported as the probability of observing this many births would be
0.00000137.
B) The belief is not supported as the probability of observing this many births is 0.00000137.
C) The belief is not supported as the probability of observing this many births is 0.185 .
D) The belief is supported as the probability of observing this many births would be 0.185 .
Q. 5Suppose the number of babies born each hour at a hospital follows a Poisson distribution with a
mean of 7. Find the probability that exactly two babies will be born during a particular 1-hour
period at this hospital.
A) 0.159580 B) 0.002793 C) 0.000742 D) 0.022341
Q. 6According to the empirical rule, z-scores of less than -3 or greater than 3 occur very infrequently
for data from a mounded and symmetric distribution
A) True B) False
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