(A) Average = 10 years (Given) and y = 2x
\(\therefore \frac{8 + 5+ 14 + x + 8 + y + 11+ 9 + 8 + 7}{10}= 10\)
⇒ \(70 + x +y = 100\)
⇒ \(x + 4 = 30\)
⇒ \(x + 2x = 30\)
⇒ \(x = \frac{30}3 = 10 \) years
& \(y = 2 \times 10 = 20\) years
(B) Increasing order of ages of these patients are 5, 7, 8, 8, 8, 9, 10, 11, 14, 20
n = 10 when is even
\(\therefore \) Median = \(\frac{\frac{10}2th \,term + (\frac{10}2 + 1)th\,term}2\)
\(= \frac{8 + 9}2\)
\(= 8.5\)
(C)
Ages |
5 |
7 |
8 |
9 |
10 |
11 |
14 |
20 |
No. of patients |
1 |
1 |
3 |
1 |
1 |
1 |
1 |
1 |
(D) Mean \( = \frac{\sum X}n =\frac{100}{10} = 10\)
Variance \(=\frac{\sum X^2}n - 10^2\)
\(= \frac{25 + 49 + 64 \times 3 + 81 + 100 + 121 + 196 + 400}{10}-100\)
\( =\frac{1164}{10} - 100\)
\(= 116.4 - 100\)
\(= 16.4\)