A research team is working on a project to study the time (in seconds) for high school male runners to finish a 400-meter race. Jimmy, a junior researcher in the team, has randomly selected a sample of 25 male runners from a high school and the time (in seconds) for each of them to complete a 400-meter race was recorded. The sample mean running time was 53 seconds. It is assumed that the running time in a 400-meter race follows a normal distribution with a population standard deviation of 5.5 seconds. (a) Give a point estimate of the population mean running time for a 400-meter race. (b) Calculate the sampling error at 95% confidence level. (c) Construct a 95% confidence interval estimate of the population mean running time for a 400-meter race.
A research team is working on a project to study the time (in seconds) for high school male runners to finish a 400-meter race. Jimmy, a junior researcher in the team, has randomly selected a sample of 25 male runners from a high school and the time (in seconds) for each of them to complete a 400-meter race was recorded. The sample mean running time was 53 seconds. It is assumed that the running time in a 400-meter race follows a normal distribution with a population standard deviation of 5.5 seconds. (a) Give a point estimate of the population mean running time for a 400-meter race. (b) Calculate the sampling error at 95% confidence level. (c) Construct a 95% confidence interval estimate of the population mean running time for a 400-meter race.
A research team is working on a project to study the time (in seconds) for high school male runners to finish a 400-meter race. Jimmy, a junior researcher in the team, has randomly selected a sample of 25 male runners from a high school and the time (in seconds) for each of them to complete a 400-meter race was recorded. The sample mean running time was 53 seconds. It is assumed that the running time in a 400-meter race follows a normal distribution with a population standard deviation of 5.5 seconds. (a) Give a point estimate of the population mean running time for a 400-meter race. (b) Calculate the sampling error at 95% confidence level. (c) Construct a 95% confidence interval estimate of the population mean running time for a 400-meter race.
A research team is working on a project to study the time (in seconds) for high school male runners to finish a 400-meter race. Jimmy, a junior researcher in the team, has randomly selected a sample of 25 male runners from a high school and the time (in seconds) for each of them to complete a 400-meter race was recorded. The sample mean running time was 53 seconds. It is assumed that the running time in a 400-meter race follows a normal distribution with a population standard deviation of 5.5 seconds. (a) Give a point estimate of the population mean running time for a 400-meter race. (b) Calculate the sampling error at 95% confidence level. (c) Construct a 95% confidence interval estimate of the population mean running time for a 400-meter race.
Transcribed Image Text:The entries in Table II are values for which the area to their right under the
distribution with given degrees of freedom (the gray area in the figuure) is equal
to a .
t
TABLE II
VALUE OFt
d.f.
f0.050
f0.025
fo.010
f0.005
d.f
1
6.314
12.706
31.821
63.657
1
2.920
4.303
6.965
9.925
2.353
3.182
4.541
5.841
4
2.132
2.776
3.747
4.604
4
5
2.015
2.571
3.365
4.032
1.943
2.447
3.143
3.707
6
7
1.895
2.365
2.998
3.499
7
1.860
2.306
2.896
3.355
9
1.833
2.262
2.821
3.250
9
10
1.812
2.228
2.764
3.169
10
11
1.796
2.201
2.718
3.106
11
12
1.782
2.179
2.681
3.055
12
13
1.771
2.160
2.650
3.012
13
14
1.761
2.145
2.624
2.977
14
15
1.753
2.131
2.602
2.947
15
16
1.746
2.120
2.583
2.921
16
17
1.740
2.110
2.567
2.898
17
18
1.734
2.101
2.552
2.878
18
19
1.729
2.093
2.539
2.861
19
20
1.725
2.086
2.528
2.845
20
21
1.721
2.080
2.518
2.831
21
22
1.717
2.074
2.508
2.819
22
23
1.714
2.069
2.500
2.807
23
24
1.711
2.064
2.492
2.797
24
25
1.708
2.060
2485
2.787
25
26
1.706
2.056
2.479
2.779
26
27
1.703
2.052
2.473
2.771
27
28
1.701
2.048
2.467
2.763
28
29
1.699
2.045
2.462
2.756
29
Inf.
1.645
1.960
2.326
2.576
In.
Definition Definition Method in statistics by which an observation’s uncertainty can be quantified. The main use of interval estimating is for describing a range that is made by transforming a point estimate by determining the range of values, or interval within which the population parameter is likely to fall. This range helps in measuring its precision.
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