In: Statistics and Probability
22a. Dr. Suzan Heverling claims that the number of births by day of week is not uniformly distributed. To test this claim you randomly select 700 births from a recent year and record the day of week on which each takes place. The table below shows the results. At a 10% significance level test the doctor’s claim.
DAY FREQUENCY
Sun 68
Mon 108
Tue 115
Wed 113
Thu 111
Fri 108
Sat 77
b. Two out of every five college graduates find a job in their field of study. If Anchorage, Alaska has 1500 college graduates this semester; find the mean variance and standard deviation of college graduates that did not find a job in their field of study.
(a) The hypothesis being tested is:
H0: The number of births by day of week is uniformly distributed
Ha: The number of births by day of week is not uniformly distributed
observed | expected | O - E | (O - E)² / E |
68 | 100.000 | -32.000 | 10.240 |
108 | 100.000 | 8.000 | 0.640 |
115 | 100.000 | 15.000 | 2.250 |
113 | 100.000 | 13.000 | 1.690 |
111 | 100.000 | 11.000 | 1.210 |
108 | 100.000 | 8.000 | 0.640 |
77 | 100.000 | -23.000 | 5.290 |
700 | 700.000 | 0.000 | 21.960 |
21.96 | chi-square | ||
6 | df | ||
.0012 | p-value |
The test statistic is 21.96.
The p-value is 0.0012.
Since the p-value (0.0012) is less than the significance level (0.10), we can reject the null hypothesis.
Therefore, we can conclude that the number of births by day of week is not uniformly distributed.
(b) p = 3/5 = 0.6
n = 1500
Mean = 0.6*1500 = 900
Varaince = 1500*0.6*0.4 = 360
Standard deviation = 1500*0.6*0.4 = 18.97
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