Question
A psychologist is interested in the mean IQ score of a given group of children. It...
A psychologist is interested in the mean IQ score of a given group of children. It is known that the IQ scores of the group have a standard deviation of 12. The psychologist randomly selects 80 children from this group and finds that their mean IQ score is 112. Based on this sample, find a 90% confidence interval for the true mean IQ score for all children of this group. Then complete the table below.
Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place.
A. What is the lower limit of the 90% confidence interval?
B. What is the upper limit of the 90% confidence interval?
Homework Answers
Answer #1
90% confidence interval for 
is
- Z
/2
* 
/ sqrt(n) <
<
+ Z/2
*
/ sqrt(n)
112 - 1.645 * 12 / sqrt(80) <
< 112 + 1.645 * 12 / sqrt(80)
109.8 <
< 114.2
A) Lower limit = 109.8
B) Upper limit = 114.2
Not the answer you're looking for?
Similar Questions
A psychologist wants to estimate the standard deviation of IQ scores. It is widely believed that...
A psychologist wants to estimate the standard deviation of IQ
scores. It is widely believed that IQ scores follow a normal
distribution. Her random sample of 25 IQ scores has a mean of 97.4
and a standard deviation of 17.2. Find the 99% confidence interval
for the population standard deviation based on this sample. Then
complete the table below. Carry your intermediate computations to
at least three decimal places. Round your answers to at least two
decimal places. (If necessary,...
A psychologist wants to estimate the standard deviation of IQ scores. It is widely believed that...
A psychologist wants to estimate the standard deviation of IQ
scores. It is widely believed that IQ scores follow a normal
distribution. Her random sample of
25
IQ scores has a mean of
99
and a standard deviation of
13.2
. Find the
99%
confidence interval for the population standard deviation based
on this sample. Then complete the table below.
Carry your intermediate computations to at least three decimal
places. Round your answers to at least two decimal places. (If...
An existing inventory for a test measuring self-esteem indicates that the scores have a standard deviation...
An existing inventory for a test measuring self-esteem indicates
that the scores have a standard deviation of 8. A psychologist gave
the self-esteem test to a random sample of 70 individuals, and
their mean score was 62. Construct a 95% confidence interval for
the true mean of all test scores. Then complete the table below.
Carry your intermediate computations to at least three decimal
places. Round your answers to one decimal place. (If necessary,
consult a list of formulas.)
What...
A laboratory in Washington is interested in finding the mean chloride level for a healthy resident...
A laboratory in Washington is interested in finding the mean
chloride level for a healthy resident in the state. A random sample
of
70
healthy residents has a mean chloride level of
102
mEq/L. If it is known that the chloride levels in healthy
individuals residing in Washington have a standard deviation of
42
mEq/L, find a
95%
confidence interval for the true mean chloride level of all
healthy Washington residents. Then complete the table below.
Carry your intermediate computations...
The mean diastolic blood pressure for a random sample of 70 people was 94 millimeters of...
The mean diastolic blood pressure for a random sample of
70
people was
94
millimeters of mercury. If the standard deviation of individual
blood pressure readings is known to be
8
millimeters of mercury, find a
90%
confidence interval for the true mean diastolic blood pressure
of all people. Then complete the table below.
Carry your intermediate computations to at least three decimal
places. Round your answers to one decimal place.
What is the lower limit of the
90%
confidence...
We are interested in the mean IQ score of seventh-grade girls in a Midwest school district....
We are interested in the mean IQ score of seventh-grade girls in
a Midwest school district. Here are the scores for 31 randomly
selected seventh-grade girls in the district:
114 100 104 89 102 91 114 114 103 105
108 130 120 132 111 128 118 119 86 72
111 103 74 112 107 103 98 96 112 112 93
These scores follow a Normal distribution with standard deviation σ
= 15. Treat these 31 girls as an SRS of...
The scores on an examination in economics are approximately normally distributed with mean 500 and an...
The scores on an examination in economics are approximately
normally distributed with mean 500 and an unknown standard
deviation. The following is a random sample of scores from this
examination. 422, 437, 472, 502, 534 Send data to Excel Find a 90%
confidence interval for the population standard deviation. Then
complete the table below. Carry your intermediate computations to
at least three decimal places. Round your answers to at least two
decimal places. (If necessary, consult a list of formulas.)...
An IQ test is given to a random sample of 10 children from Oldham, yielding a...
An IQ test is given to a random sample of 10 children from
Oldham, yielding a sample mean of 100.0 and sample variance of 90.
A 90% confidence interval , (assuming the population sampled from
is normal) for the mean IQ of children in this area is given by (to
one decimal place):
(93.2,106.8)
(94.1,105.6)
(95.1,104.9)
(93.3,106.7)
(94.5,105.5)
The lifetime of a certain brand of electric light bulb is known to have a standard...
The lifetime of a certain brand of electric light bulb is known
to have a standard deviation of
51
hours. Suppose that a random sample of
150
bulbs of this brand has a mean lifetime of
481
hours. Find a
90%
confidence interval for the true mean lifetime of all light
bulbs of this brand. Then complete the table below.
Carry your intermediate computations to at least three decimal
places. Round your answers to one decimal place. (If necessary,
consult...
The lifetime of a certain brand of battery is known to have a standard deviation of...
The lifetime of a certain brand of battery is known to have a
standard deviation of 16 hours. Suppose that a random sample of 50
such batteries has a mean lifetime of 37.6 hours. Based on this
sample, find a 90% confidence interval for the true mean lifetime
of all batteries of this brand. Then complete the table below.
Carry your intermediate computations to at least three decimal
places. Round your answers to one decimal place. ( If necessary,
consult...
ADVERTISEMENT
Need Online Homework Help?
Get Answers For Free
Most questions answered within 1 hours.
ADVERTISEMENT
Active Questions
asked 2 minutes ago
asked 7 minutes ago
asked 15 minutes ago
asked 19 minutes ago
asked 21 minutes ago
asked 48 minutes ago
asked 50 minutes ago
asked 1 hour ago
asked 1 hour ago
asked 1 hour ago
asked 1 hour ago
asked 1 hour ago