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Question
The following table shows the electricity (in units) used by 25 families of Eklara village in a month of May. Complete the table and answer the following questions.
| Electricity used (units) `bb(x_i)` |
No. of Families (frequency) `bb(f_i)` |
`bb(f_ix_i)` |
| 30 | 7 | _________ |
| 45 | 2 | __________ |
| 60 | 8 | __________ |
| 75 | 5 | __________ |
| 90 | 3 | __________ |
| N = _________ | `sum f_ix_i` = ______ |
- How many families use 45 units electricity?
- State the score, the frequency of which is 5.
- Find N, and `sum f_ix_i`
- Find the mean of electricity used by each family in the month of May.
Solution
| Electricity used (units) `bb(x_i)` |
No. of Families (frequency) `bb(f_i)` |
`bb(f_ix_i)` |
| 30 | 7 | 30 × 7 = 210 |
| 45 | 2 | 45 × 2 = 90 |
| 60 | 8 | 60 × 8 = 480 |
| 75 | 5 | 75 × 5 = 375 |
| 90 | 3 | 90 × 3 = 270 |
| N = 25 | `sum f_ix_i` = 1425 |
(1) 2 families use 45 units of electricity.
(2) The score with a frequency of 5 is 75 units.
(3) N = 25, and `sum f_ix_i`= 1425
(4) Since,
= `1425/25`
= 57
So, the mean of electricity used by each family in the month of May is 57.
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