In Exercises 7-18, find the indicated area under the standard normal curve. If convenient, use
technology to find the area
7. To the left of z = 0.33
12. To the right of z = 0.015
14. Between z = -1.55 and z = 1.04
34. The daily surface concentration of carbonyl sulfide on the Indian Ocean is
normally distributed, with a mean of 9.1 picomoles per liter and a standard
deviation of 3.5 picomoles per liter. Find the probability that on a randomly
selected day, the surface concentration of carbonyl sulfide on the Indian
Ocean is
(a) between 5.1 and 15.7 picomoles per liter.
(b) between 10.5 and 12.3 picomoles per liter.
(c) more than 11.1 picomoles per liter. (Source: Atmospheric Chemistry and
Physics)
43. Find the z-score that has 30.5% of the distribution's area to its right.
44. Find the positive z-score for which 94% of the distribution's area lies
between -z and z.
In Exercises 53 and 54, find the mean and standard deviation of the indicated
sampling distribution of sample means. Then sketch a graph of the sampling
distribution.
54. The test scores for the Law School Admission Test (LSAT) in a recent year
are normally distributed, with a mean of 155.69 and a standard deviation
of 5.05. Random samples of size 40 are drawn from this population, and the
mean of each sample is determined. (Source: Law School Admission Council)
Find the mean, variance (if you can do )
62. A survey of U.S. likely voters found that 11% think Congress is doing a
good or excellent job. You randomly select 45 U.S. likely voters and ask
them whether they think Congress is doing a good or excellent job. (Source:
Rasmussen Reports)