Mathematics
Thirty women were examined in a hospital by a doctor and the number of heartbeats per minute were recorded and summarised as follows. Find the mean heartbeats per minute for these women, choosing a suitable method.
| Number of heartbeats per minute | Number of women |
|---|---|
| 65 - 68 | 2 |
| 68 - 71 | 4 |
| 71 - 74 | 3 |
| 74 - 77 | 8 |
| 77 - 80 | 7 |
| 80 - 83 | 4 |
| 83 - 86 | 2 |
Related Questions
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 leaves.
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.
100 surnames were randomly picked up from a local telephone directory and the frequency distribution of the number of letters in the English alphabets in the surnames was obtained as follows :
Number of letters Number of surnames 1 - 4 6 4 - 7 30 7 - 10 40 10 - 13 16 13 - 16 4 16 - 19 4 Determine the median number of letters in the surnames. Find the mean number of letters in the surnames? Also, find the modal size of the surnames.
The distribution below gives the weights of 30 students of a class. Find the median weight of the students.
Weight (in kg) Number of students 40 - 45 2 45 - 50 3 50 - 55 8 55 - 60 6 60 - 65 6 65 - 70 3 70 - 75 2