Question

1. Let the mean be 100 and the standard deviation be 15 for the normal distribution for adult IQs in North Carolina.

a. Use the empirical rule to find what proportion of the data is located between 85 and 115.

b. How about 100 and 130?

c. Find the z-score for the following data points and explain what these mean: i. x = 80 ii. x = 109

Answer #1

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Q1-. A normal distribution has a mean of 15 and a standard
deviation of 2. Find the value that corresponds to the 75th
percentile. Round your answer to two decimal places.
Q2-.Tyrell's SAT math score was in the 64th percentile. If all
SAT math scores are normally distributed with a mean of 500 and a
standard deviation of 100, what is Tyrell's math score? Round your
answer to the nearest whole number.
Q3-.Find the z-score that cuts off an area...

Q1-. A normal distribution has a mean of 15 and a standard
deviation of 2. Find the value that corresponds to the 75th
percentile. Round your answer to two decimal places.
Q2-.Tyrell's SAT math score was in the 64th percentile. If all
SAT math scores are normally distributed with a mean of 500 and a
standard deviation of 100, what is Tyrell's math score? Round your
answer to the nearest whole number.
Q3-.Find the z-score that cuts off an area...

A normal distribution has a mean of 60 and a standard deviation
of 16. For each of the following scores, indicate whether the body
is to the right or the left of the score and find the proportion of
the distribution located in the body X = 64 X = 80 X = 52 X =
28

The mean of a normally distributed data set is 112, and the
standard deviation is 18.
a) Use the Empirical Rule to find the probability
that a randomly-selected data value is greater than 130.
b) Use the Empirical Rule to find the probability
that a randomly-selected data value is greater than 148.
A psychologist wants to estimate the proportion of people in a
population with IQ scores between 85 and 130. The IQ scores of this
population are normally distributed...

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 a normal distribution with mean 100 and standard deviation
10, find the probability of obtaining a value greater than or equal
to 80 but less than or equal to 115. Using excel please.

Suppose that IQs of adult Canadians follow a normal distribution
with standard deviation 15. A random sample of 30 adult Canadians
has a mean IQ of 112.
At the 7% level of significance, we would like to test whether
the true mean IQ of all adult Canadians is less than 115. What is
the P-value for the appropriate test of significance? Keep 4
decimal places in intermediate calculations and report your final
answer to 4 decimal places.

Scores of an IQ test have a bell-shapped distribution
with a mean of 100 and standard deviation of 15. Use the empirical
rule to determine the following.
A.) What percentage of people has an IQ between 55 and
145?
B.) What percentage of people has an IQ score less than
85 or greater than 115?
C.) What percentage of people has an IQ score greater
than 145?
(Type an integer or decimal.)

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?...

Given a mean of 100 and a standard deviation of 10, convert the
random variables to Z-scores, then use a standard normal table
below to find the probabilities.
1. Pr[75 ≤ X ≤ 100]=
2. Pr[85 ≤ X ≤ 125] =
3. Pr[X ≥ 115] =

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