Download Chap 3 Review

Chapter 3 Review
Prob/Stat
Name_______________________________
Date____________________Period______
1. Owners of a minor league baseball team believe the normal model is useful in projecting
the number of fans who will attend home games. They use a mean of 8500 fans and a
standard deviation of 1500 fans.
a. Draw and clearly label this model.
b. Between what two values are 95% of the games represented?
c. What percentage of the games have more than 11,500 fans in attendance?
d. What percentage of games have between 5500 and 8500 fans in attendance?
Use the standard normal table to find the following proportions.
2. z < 1.28
3. z > −0.74
4. −2.15 < z < 1.55
5. A student took the SAT and ACT tests in preparation for college admissions. The SAT
scores are normally distributed with a mean of 1000 and a standard deviation of 200. The
ACT scores are normally distributed with a mean of 20 and a standard deviation of 5. The
student got a 1080 on the SAT and a 27 on the ACT. On which test did the student score
better?
6. The green turtle migrates across the Southern Atlantic in the winter, swimming great
distances. A study found that the mean migration distance was 2200 kilometers and the
standard deviation was 625 kilometers. Assuming that the distances are normally distributed,
find the probability that a randomly selected green turtle migrates a distance of
a. less than 1900 kilometers.
b. between 2000 and 2500 kilometers.
c. greater than 2450 kilometers.
7. Chocolate bars produced by a certain machine are labeled as 8.0 oz. The distribution of
the actual weights of these chocolate bars is normal with a mean of 8.1 oz. and a standard
deviation of 0.1 oz. A chocolate bar is considered underweight if it weighs less than 8.0 oz.
a. What is the proportion of chocolate bars weighing less than 8.0 oz?
b. What is the proportion of chocolate bars with weights between 8.2 and 8.3 oz?
c. How should the chocolate bar wrappers be labeled so only 1% of bars produced are
underweight?
8. A zoo is looking for an unusually large jaguar for its “Big Cats” display. The body length
(excluding the tail) of jaguars is known to have a mean of 1.4 meters and a standard
deviation of 0.20 meter. Suppose the zoo defines “unusually large” as the top 15% of jaguars
in body length. Assuming that the body lengths are normally distributed, what requirement
would you place on their body length?
9. The times for completing one circuit of a bicycle course are normally distributed with a
mean of 72.5 minutes and a standard deviation of 6.5 minutes. An association wants to
sponsor a race, but only wants the top 25% of riders included. In a trial run, what should be
the cutoff time?
10. To completely specify the shape of a Normal distribution, you must give
a. the mean and the standard deviation.
b. the five-number summary.
c. the mean and the median.
11. The figure below shows a Normal curve. The mean of the distribution is
a. 0
b. 2
c. 3
12. The standard deviation of the Normal distribution in the figure below is
a. 2
b. 3
c. 5