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प्रश्न
The lengths of 40 leaves of a plant are measured correct to the nearest millimeter, and the data obtained is represented in the following table:
| Length (in mm) | Number of leaves |
| 118−126 | 3 |
| 127–135 | 5 |
| 136−144 | 9 |
| 145–153 | 12 |
| 154–162 | 5 |
| 163–171 | 4 |
| 172–180 | 2 |
Find the mean length of the leaves.
उत्तर
|
Length |
Number of |
CI |
Mid x |
d |
fd |
|
118−126 |
3 |
117.5 − 126.5 |
122 |
-27 |
-81 |
|
127−135 |
5 |
126.5 − 135.5 |
131 |
-18 |
-90 |
|
136−144 |
9 |
135.5 − 144.5 |
140 |
-9 |
-81 |
|
145−153 |
12 |
144.5 − 153.5 |
a = 149 |
0 |
0 |
|
154−162 |
5 |
153.5 − 162.5 |
158 |
9 |
45 |
|
163−171 |
4 |
162.5 − 171.5 |
167 |
18 |
72 |
|
172−180 |
2 |
171.5 − 180.5 |
176 |
27 |
54 |
Mean = `"a" + (sum"fd")/(sum"f")`
= `149 + (-8)/40`
= 149 - 2.025
= 146.975
Average length of the leaves = 146.975.
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