Question

A normal distribution has a mean of 50 and a standard deviation of 12. 68% of the distribution can be found between what two numbers?

Select one:

a. 38 and 62

b. 44 and 56

c. 16 and 86

d. 42 and 58

Answer #1

solution

Given that,

mean = = 50

standard deviation = = 12

middle 68% of score is

P(-z < Z < z) = 0.68

P(Z < z) - P(Z < -z) = 0.68

2 P(Z < z) - 1 = 0.68

2 P(Z < z) = 1 + 0.68 = 1.68

P(Z < z) =1.68 / 2 = 0.84

P(Z < 0.99) = 0.84

z ± 0.99 using z table

Using z-score formula

x= z * +

x= ±0.99*12+50

x= 38 and 62

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?

The mean of a normal probability distribution is 320; the
standard deviation is 18.
a)About 68% of the observations lie between what two values?
Value #1_____. Value #2______.
b)About 95% of the observations lie between what two values?
Value#1_____. Value#2_____.
c)Practically all of the observations lie between what two
values? Value#1______. Value#2______.

For a normal distribution with a mean of u = 60 and a standard
deviation of o = 10,
find the proportion of the population corresponding to each of
the following.
a. Scores greater than 65.
b. Scores less than 68.
c. Scores between 50 and 70.

The mean of a normal probability distribution is 380; the
standard deviation is 10.
a. 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?

The mean of a normal probability distribution is 380; the
standard deviation is 18. a. About 68% of the observations lie
between what two values? b. About 95% of the observations lie
between what two values? c. Practically all of the observations lie
between what two values?

1.23)
A population distribution of scores has a mean = 50 and a
standard deviation of 4. Researchers plan to take a sample size of
N = 64. Based on the central limit theorem, 68.26% of all
possible sample means are between the sample means of ______.
a.
46 and 54
b.
42 and 58
c.
49.5 and 50.5
d.
47 and 53
1.32)
With a p value of .10 and an α of .05, should you
reject or fail...

a data set has a mean of 50 and a standard deviation of 10. if
the distribution is symmetrical then what percent is between
(20,80)?
choices are: 68%, 75%, 95%, 88.89%, 99.7%

a.) Given a normal distribution with population standard
deviation of 21 and a mean of μ = 29. If a random sample
of size 62 is drawn, find P(29 ≤ x ≤ 31).
Round to three decimal places.
b.) Find the positive z value such that 89% of the
standard normal curve lies between –z and z. (Use
2 decimal places.)
c.) For a standard normal curve, find the area between
z = 0.28 and z = 1.95. (Use 4...

The mean of a normal probability distribution is 360; the
standard deviation is 14.
(a)
About 68 percent of the observations lie between what two
values?
Value 1
Value 2
(b)
About 95 percent of the observations lie between what two
values?
Value 1
Value 2
(c)
Practically all of the observations lie between what two
values?
Value 1
Value 2

6) [True or False] Standard deviation can be
negative.
A) TRUE
B) FALSE
7. A random sample of 40 college professors is selected
from all professors at a university.
The following list contains their ages.
65, 45, 44, 38, 55, 55, 49, 42, 43, 22, 52, 58, 52, 38,
56, 34, 53, 36, 50, 36
34,
68, 43, 56, 37, 35, 28, 30, 26, 26, 53, 30, 37, 55,
28, 39, 26, 31, 37, 50
Z score for 55 is?

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