Unformatted text preview: Student: Grady Simonton Course: Math119: Elementary Statistics - Spring 2.010 - CRN: 49239
Instructor: Shawn Parvini - 16 weeks Date: 2/18/10 Book: Triola: Elementary Statistics, 11e
Time: 11:29 ANI Six different second-year medical students at Bellevue Hospital measured the blood pressure of the same person. The
systolic readings (in mmHg) are listed below. Find the range, variance, and standard deviation for the given sample data.
If the subject's blood pressure remains constant and the medical students correctly apply the same measurement
technique, what should be the value of the standard deviation? 149 136 125 128 121 133 Recall that the range of a set of data is the difference between the maximum value and the minimum value. Note that the maximum blood pressure was 149 mmHg and the minimum blood pressure was 121 mmHg. Use this to
the ﬁnd the range. Range = 149 - 121 =28 mmHg Find the standard deviation, s, of the data using the formula below. Remember that the sample variance is s2. S: [aim—(w
n(n-l) To use the formula above, ﬁrst ﬁnd the values for n, 2);, and 2x2.
Zx=149+136+125 +128+121+133=792 Zx2= 1492+1362+1252+1282+1212+1332= 105,036 Substitute Z x, 2 x2, and 11 into the formula below to ﬁnd the sample variance, sz. n(n - l)
= 6005,0315) — (1'92)2 =98.4mrnH 2
6(6- 1) g Finally, ﬁnd the square root of s2 to ﬁnd the standard deviation, 5. ,= [Emma—(2x?
= 98.4 a9.9mmHg To determine what the value of the standard deviation should be if the subject's blood pressure remains constant and the
medical students correctly apply the same measurement technique, note that the value of the standard deviation is
usually positive. It is zero only when all of the data values are the same number. Page 1 ...
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- Spring '10