Consider two groups, say G1 and G2, comprising of 10 and 30 patients, respectively. Suppose that mean diastolic blood pressures of patients in groups G1 and G2 are 80 mmHg and 100 mmHg, respectively, and the corresponding variances are 4 mmHg2 and 2 mmHg2, respectively. Let X̅, S2, C and R, respectively, denote the mean (in mmHg), variance (in mmHg2), coefficient of variation (in percentage) and range (in mmHg) of the diastolic blood pressures of the combined group (the two groups combined). Then which of the following statements are true?
(Note: For observations x1, x2, ..., xn, variance is defined by \(\frac{1}{n} \sum_{i=1}^n\left(x_i-̅{x}\right)^2\), where \(\bar{x}=\frac{1}{n} \sum_{j=1}^n x_j\).)
1
\(\bar{X}=95\)
2
S2 = 77
3
\(C>\frac{180}{19}\)
4
R > 8