Using the data of regarding heart rates collected in table below. Use the sample
ID: 2935577 • Letter: U
Question
Using the data of regarding heart rates collected in table below. Use the sample mean and standard deviation as estimates of the population parameters. For the before-exercise data, what heart rate separates the top 10% from the other values? For the after-exercise data, what heart rate separates the bottom 10% from the other values? If a student were selected at random, what is the probability that her or his heart before exercise was less than 72? If 25 students were selected at random, what is the probability that their mean heart rate before exercise was less than 72?
Group 1 Results
Group 2 Results
60
80
78
122
84
98
88
128
65
120
56
90
89
110
74
88
90
120
80
90
68
80
68
94
69
100
63
99
72
123
80
90
75
92
79
82
75
96
55
68
70
89
64
82
83
92
78
87
76
103
77
95
75
105
89
120
70
90
70
114
48
69
72
98
76
124
65
75
2481
3313
Group 1 Results
Group 2 Results
60
80
78
122
84
98
88
128
65
120
56
90
89
110
74
88
90
120
80
90
68
80
68
94
69
100
63
99
72
123
80
90
75
92
79
82
75
96
55
68
70
89
64
82
83
92
78
87
76
103
77
95
75
105
89
120
70
90
70
114
48
69
72
98
76
124
65
75
2481
3313
Explanation / Answer
before-exercise data, what heart rate separates the top 10% from the other values
= zcritical * sd + mean
= 1.282 * 9.983 + 72.97
= 85.77 or 86
=> after-exercise data, what heart rate separates the bottom 10% from the other values
= zcritical * sd + mean
= -1.282 * 16.32 + 97.44
= 76.52 or 77
probability that her or his heart before exercise was less than 72
= p[x < 72]
= p[Z < 72-72.97/9.983]
= p[Z < -0.097]
= 0.4614
If 25 students were selected at random, what is the probability that their mean heart rate before exercise was less than 72
= p[xbar < 72]
= p[Z < (72-72.97)*5/9.983]
= p[Z < -0.486]
= 0.3135
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