Jambmaths question:
|
Class width |
3 – 5 |
6 – 8 |
9 – 11 |
|
Frequency |
2 |
2 |
2 |
Find the standard deviation of the above distribution
Option A:
$\sqrt{7}$
Option B:
$\sqrt{6}$
Option C:
$\sqrt{5}$
Option D:
$\sqrt{4}$
Jamb Maths Solution:
|
Class interval |
Mid-class X |
f |
fx |
D=$x-\overline{x}$ |
D2 |
fD2 |
|
3 – 5 |
4 |
2 |
8 |
– 3 |
9 |
18 |
|
6 – 8 |
7 |
2 |
14 |
0 |
0 |
0 |
|
9 – 11 |
10 |
2 |
20 |
3 |
9 |
18 |
|
Total |
|
|
42 |
|
|
36 |
$\overline{x}=\frac{\sum fx}{\sum f}=\frac{42}{6}=7$
$\sigma =\sqrt{\frac{\sum f{{(x-\overline{x})}^{2}}}{\sum f}}=\sqrt{\frac{36}{6}}=\sqrt{6}$
Jamb Maths Topic:
Year of Exam: