Class Interval | 50-70 | 70-90 | 90-110 | 110-130 | 130-150 | 150-170 |
---|---|---|---|---|---|---|
Number of Students | 15 | 21 | 32 | 19 | 8 | 5 |
Marks | 0-5 | 5-10 | 10-15 | 15-20 | 20-25 |
---|---|---|---|---|---|
No. of students | 10 | 18 | 42 | 13 | 7 |
The lengths of 40 leaves of a plant are measured correct to the nearest millimetre, 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 median length of the leaves.
(Hint : The data needs to be converted to continuous classes for finding the median, since the formula assumes continuous classes. The classes then change to 117.5 - 126.5, 126.5 - 135.5, . . ., 171.5 - 180.5.)
The following frequency distribution gives the monthly consumption of electricity of 68 consumers of a locality. Find the median, mean and mode of the data and compare them
Monthly consumption | Number of consumers |
---|---|
65 - 85 | 4 |
85 - 105 | 5 |
105 - 125 | 13 |
125 - 145 | 20 |
145 - 165 | 14 |
165 - 185 | 8 |
185 - 205 | 4 |
Class interval | Frequency |
---|---|
0 - 10 | 5 |
10 - 20 | x |
20 - 30 | 20 |
30 - 40 | 15 |
40 - 50 | y |
50 - 60 | 5 |
Total | 60 |
The following table gives the distribution of the life time of 400 neon lamps :
Life time (in hours) | Number of lamps |
---|---|
1500 - 2000 | 14 |
2000 - 2500 | 56 |
2500 - 3000 | 60 |
3000 - 3500 | 86 |
3500 - 4000 | 74 |
4000 - 4500 | 62 |
4500 - 5000 | 48 |
Find the median life time of a lamp.