In: Statistics and Probability
The annual earnings (in dollars) of 35 randomly selected microbiologists are shown in the data table. Use the data to (a) find the sample mean, (b) find the sample standard deviation, and (c) construct a 98% confidence interval for the population mean.
100,700 81,419 77,543 68,099 51,620 67,741 94,804 66,410 79,448 73,448 44,319 86,757 60,644 58,151 54,634 78,891
47,896 98,388 80,793 92,543 63,410 75,100 50,972 60,936 91,207 84,375 80,002 63,941 74,232 56,985 46,910 89,548
76,023 62,168 82,712
The table given below ,
X | |
100700 | 819155344.4 |
81419 | 87233545.21 |
77543 | 29854093.93 |
68099 | 15841275.61 |
51620 | 418575182 |
67741 | 18819198.37 |
94804 | 516420625.5 |
66410 | 32138808.19 |
79448 | 54300539.83 |
73448 | 1873859.832 |
44319 | 770623707.2 |
86757 | 215440454.9 |
60644 | 130761740.7 |
58151 | 193992248.2 |
54634 | 304331862.9 |
78891 | 46401845.37 |
47896 | 584822809.3 |
98388 | 692157693 |
80793 | 75931878.93 |
92543 | 418770793.9 |
63410 | 75153468.19 |
75100 | 9125776.392 |
50972 | 445510092.6 |
60936 | 124168900.5 |
91207 | 365876175.9 |
84375 | 151188910.9 |
80002 | 62772185.95 |
63941 | 66228834.37 |
74232 | 4634935.352 |
56985 | 227832156.7 |
46910 | 633484098.2 |
89548 | 305162117.8 |
76023 | 15554268.33 |
62168 | 98230101.43 |
82712 | 113058349.8 |
From table ,
a) The sample mean is given by ,
b) The sample standard deviation is given by ,
c) The degrees of freedom is given by ,
d.f.=n-1=35-1=34
The critical value is given by ,
; From excel "=TINV(0.02,34)"
Therefore , the 98% confidence interval for the population mean is given by ,