Question

for a normal distribution with mean 100 and standard deviation of 20, calculate: a) the percentage of the values between 100 and 120 b) the percentage of the values between 60 and 80 c) the percentage of the values between 80 and 140

Answer #1

(a)

= mean = 100

= SD = 20

To find P(100 < X < 120):

Z = (120 - 100)/20 = 1

Table of Area Under Standard Normal Curve gives area = 0.3413 = 34.13 %

So,

Answer is:

**34.13** %

(b)

To find P(60 < X < 80):

Case 1: for X from 60 to mid value:

Z = (60 - 100)/20 = - 2

Table gives area = 0.4772

Case 2: For X from 80 to mid value:

Z = (80 - 100)/20 = - 1

Table gives area = 0.3413

So,

P(60 < X < 80) = 0.4772 - 0.3413 = 0.1359 = 13.59 %

So,

Answer is:

**13.59 %**

(c)

P(80 < X < 140):

Case 1: For X from 80 to mid value:

Z = (80 - 100)/20 = - 1

Table gives area = 0.3413

Case 2: For X from mid value to 140:

Z = (140-100)/20 = 2

Table gives area = 0.4772

So,

P(80 < X < 140) = 0.0.3413 + 0.4772 = 0.8185 = 81.85 %

So,

Answer is:

**81,85** %

Given a normal distribution with mean of 100 and standard
deviation of 10, what is the probability that:
a. X > 80?
b. X < 65?
c. X < 75 or X > 90?
d. Between what two X values (symmetrically distributed around
the mean) are ninety percent of the values

Given a normal distribution with Mean of 100 and Standard
deviation of 10, what is the probability that
between what two X values (symmetrically distributed around the
mean) are 80% of the values?

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

a new ‘partial correlation’
1.Describe a normal bell-shaped curve showing a mean
of 100, a standard deviation of 10 and the percentages of scores
that would fall at each standard deviation.
What % of values will fall between 90-110?
What % of values will fall between 80-120?
What % of values will fall between 70-130?
2. In a distribution with a mean of 200 and a standard
deviation of 20 what is the probability that someone will
score at or...

The mean of a normal probability distribution is 340; the
standard deviation is 20.
About 68% of the observations lie between what two values?
About 95% of the observations lie between what two values?
Practically all of the observations lie between what two
values?

A variable X follows a normal distribution with mean 20 and
standard deviation 3. Approximately 95% of the distribution can be
found between what values of X?
Select one:
a. 10 and 30
b. 17 and 23
c. 0 and 23
d. 14 and 26
e. 18 and 22

A variable X follows a normal distribution with mean 20 and
standard deviation 3. Approximately 95% of the distribution can be
found between what values of X?
Select one:
a. 0 and 23
b. 17 and 23
c. 18 and 22
d. 14 and 26
e. 10 and 30

For a normal distribution, find the percentage of data that are
(a) Within 1 standard deviation of the mean __________ % (b)
Between ?−3.5? μ − 3.5 σ and ?+2.5? μ + 2.5 σ ____________% (c)
More than 2 standard deviations away from the mean _________%

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.

e mean of a normal distribution is 540 kg. The standard
deviation is 20 kg. Refer to the table in Appendix B.1. (Round the
z values to 2 decimal places and the final answers to 4 decimal
places.) a. What is the area between 547 kg and the mean of 540 kg?
Area b. What is the area between the mean and 522 kg? Area c. What
is the probability of selecting a value at random and discovering
that it...

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 5 minutes ago

asked 11 minutes ago

asked 14 minutes ago

asked 15 minutes ago

asked 17 minutes ago

asked 22 minutes ago

asked 30 minutes ago

asked 30 minutes ago

asked 31 minutes ago

asked 41 minutes ago

asked 41 minutes ago

asked 42 minutes ago