Question

Assuming a population is normally distributed with a mean score of 100 and a standard deviation of 10.

A) What is the probability of selecting an item from the population with a score of more than 110?

B) What proportion of the population is expected to have scores above 100?

C) What is the probability of a score between 95 and 110?

D) What is the probability of a score less than 95?

E) What is the probability of a score less than 90 or more than 115?

2. A firm wants to establish an idea of the useful life of its air freshener. Tests of 100 fresheners revealed a mean useful life of 46 hours with a standard deviation of 5 hours. Develop a 95% and a 90% confidence interval for the mean useful life of all air fresheners.

Answer #1

Please post remaining question separately

6. Assume that adults have IQ scores that are normally
distributed with mean 100 and standard deviation 15. In each case,
draw the graph (optional), then find the probability of the given
scores. ROUND YOUR ANSWERS TO 4 DECIMAL PLACES
a. Find the probability of selecting a subject whose score is
less than 115. __________
b. Find the probability of selecting a subject whose score is
greater than 131.5. __________
c. Find the probability of selecting a subject whose score...

Suppose that the mean score for a critical reading test is 580
with a population standard deviation of 115 points. What is the
probability that a random sample of 500 students will have a mean
score of more than 590? Less than 575?

7. IQ scores are normally distributed with a mean of 100 and a
standard deviation of 15 points.
a. Find the probability that a randomly selected person has an
IQ less than 115.
b. Find the probability that a randomly selected person has an
IQ above 60.
c. Find the 80th percentile for IQ scores.
d. Find the probability that 20 randomly selected person has an
IQ less than 110.
e. What percentage of people have IQ scores between 60...

Students taking a standizedvIQ test had a mean score of 100 with a
standard deviation of 15. Assume that the scores are normally
distributed.
a) Find the probaility that a student had a score less than
95.
b) If 2000 students are randomly selected, how many would be
expected to have an IQ score that is less than 90?
c) What is the cut off score that would place a student in the
bottom 10%?
d) A random sample of...

IQ scores are normally distributed with a mean of 110 and a
standard deviation of 16. Find the probability a randomly selected
person has an IQ score greater than 115.

Scores on a certain test are normally distributed with a mean of
77.5 and a standard deviation 9.3.
a) What is the probability that an individual student will score
more than 90?
b) What proportion of the population will have a score between
of 70 and 85?
c) Find the score that is the 80th percentile of all tests.

With a known population mean of 100, and a known standard error
of the mean of 85, what is the probability of selecting at random a
sample whose mean is equal to 110 or greater?

For a population with a mean of u = 100 and a standard deviation
of o = 20
a. Find the z-score for each of the following X values.
X = 108 X = 115 X = 130
X = 90 X = 88 X = 95
b. Find the score ( X value) that corresponds to each of the
following z-scores.
z = -0.40 z = -0.50 z = 1.80
z = 0.75 z = 1.50 z = -1.25

For question 10, assume that adults have IQ scores that are
normally distributed with a mean of 100 and a standard deviation of
15. Find the probability that a randomly selected adult has an IQ
of the following: 10. Find the area under the standard normal curve
for the following: • Less than 115. • Greater than 131.5 • Between
90 and 110 • Between 110 and 120

IQ scores are normally distributed
with mean of 100 and a standard deviation of 15.
If MENSA only accepts people with an IQ score at the
99th percentile or higher, what is the lowest possible
IQ score you can have and still be admitted to the
organization?
Mental disability has traditionally been diagnosed for anyone
with an IQ of 70 or lower. By this standard, what proportion of the
population would meet criteria to be diagnosed with a mental
disability?...

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