3. A student suspects that the 16 data she collected for research study do not represent the target population. The data she collected represents a mean of 29 and standard deviation of 8. the population mean is 27. Assuming normality in the target population, is the student's suspicion correct? Use a 90% confidence level.

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
18th Edition
ISBN:9780079039897
Author:Carter
Publisher:Carter
Chapter10: Statistics
Section: Chapter Questions
Problem 22SGR
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Question
Please refer to the lesson (sketch also the normal curve)
II. Learning Activity:
The t-distribution, just like the z-distribution or standard normal curve, is bell-shaped and
unimodal. It is symmetric about = 0. However, it is flatter in the middle and has more area in its tail than that
of the standard normal curve. Its shape depends on the sample size . As the sample size becomes larger,
the t - distribution gets closer to the standard normal distribution.
Flatter
V
Wider area
of tails
standardi normal curve
t-distribution curve
The t-distribution is used with small samples taken from population that is approximately normal. The
z - statistic is used when ≥ 30 while t - statistic is used when <30. The t - statistic below uses the sample
deviation especially when the population variance is unknown.
#U
The t - distribution formula is:
=
where: - sample mean
-population mean
- sample size
- standard deviation of the sample mean
Example # 1
A sample of size = 20 is a random sample selected from a normally distributed population. Find the
value of such that the shaded area to the left of - is 0.05
Solution:
Find the degree of freedom 0.
0.05
0.05
y
one-tail/=
0.50
0.25
0.20
0.05
two-tails / a
1.00
0.50
0.40
0.10
df
1
0.000
1.000
1.376
6.314
2
0.000
0.816
1.061
2.920
3
0.000
0.765
0.978
2.353
***
www
19
0.000
0.688
0.861
1.729
20
0.000
0.687
0.860
1.725
A portion of the t - table
Since the distribution is symmetric about 0, then the area to the right of is 0.05 also. In the Table of t-
Critical Values, move down the first column headed df until = 19. Move to the right until the column headed
0.05 (area in one-tail) or 0.10 (area in two-tails). Therefore, D.=0.000 with 00 = 00.
Example # 2
For a t-distribution with 27 degrees of freedom, find the value of such that the area between - and
is 0.90.
Solution:
a. The degree of freedom = 27.
b.
(1)100% = 90%
(1)1 = 0.90
0.90
= 0.10 (two-tails)
== 0.05 (one-tail)
-t
t
In the Table of t-Critical Values, move down the first column headed df until = 27. Move to the right
until the column headed 0.05 (area in one-tail) or 0.10 (area in two-tails). Hence, D.00 = 0.000 with DD =
00.
1-0 =00
00=20-1
□□ = 19
NO
-t
t
Transcribed Image Text:II. Learning Activity: The t-distribution, just like the z-distribution or standard normal curve, is bell-shaped and unimodal. It is symmetric about = 0. However, it is flatter in the middle and has more area in its tail than that of the standard normal curve. Its shape depends on the sample size . As the sample size becomes larger, the t - distribution gets closer to the standard normal distribution. Flatter V Wider area of tails standardi normal curve t-distribution curve The t-distribution is used with small samples taken from population that is approximately normal. The z - statistic is used when ≥ 30 while t - statistic is used when <30. The t - statistic below uses the sample deviation especially when the population variance is unknown. #U The t - distribution formula is: = where: - sample mean -population mean - sample size - standard deviation of the sample mean Example # 1 A sample of size = 20 is a random sample selected from a normally distributed population. Find the value of such that the shaded area to the left of - is 0.05 Solution: Find the degree of freedom 0. 0.05 0.05 y one-tail/= 0.50 0.25 0.20 0.05 two-tails / a 1.00 0.50 0.40 0.10 df 1 0.000 1.000 1.376 6.314 2 0.000 0.816 1.061 2.920 3 0.000 0.765 0.978 2.353 *** www 19 0.000 0.688 0.861 1.729 20 0.000 0.687 0.860 1.725 A portion of the t - table Since the distribution is symmetric about 0, then the area to the right of is 0.05 also. In the Table of t- Critical Values, move down the first column headed df until = 19. Move to the right until the column headed 0.05 (area in one-tail) or 0.10 (area in two-tails). Therefore, D.=0.000 with 00 = 00. Example # 2 For a t-distribution with 27 degrees of freedom, find the value of such that the area between - and is 0.90. Solution: a. The degree of freedom = 27. b. (1)100% = 90% (1)1 = 0.90 0.90 = 0.10 (two-tails) == 0.05 (one-tail) -t t In the Table of t-Critical Values, move down the first column headed df until = 27. Move to the right until the column headed 0.05 (area in one-tail) or 0.10 (area in two-tails). Hence, D.00 = 0.000 with DD = 00. 1-0 =00 00=20-1 □□ = 19 NO -t t
III. Practice Exercises:
Read the following problems carefully. Analyze and solve systematically.
I SUODOSE VOU DIAve a samoie of size – 17 πom a m
that
ZINĀTN
level.
uch that the
0.00
3. A student suspects that the 16 data she collected for research study do not represent the target
population. The data she collected represents a mean of 29 and standard deviation of 8. the population mean
is 27. Assuming normality in the target population, is the student's suspicion correct? Use a 90% confidence
level.
Transcribed Image Text:III. Practice Exercises: Read the following problems carefully. Analyze and solve systematically. I SUODOSE VOU DIAve a samoie of size – 17 πom a m that ZINĀTN level. uch that the 0.00 3. A student suspects that the 16 data she collected for research study do not represent the target population. The data she collected represents a mean of 29 and standard deviation of 8. the population mean is 27. Assuming normality in the target population, is the student's suspicion correct? Use a 90% confidence level.
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