The following frequency distribution records the monthly electricity consumption (in…
MATHEMATICS · Multi-part · CBSE · Mathematics · Statistics · Statistics
Problem
The following frequency distribution records the monthly electricity consumption (in units) of 60 households in a locality. (i) Define "class mark" and "class width" for a grouped frequency table. (ii) Explain, without actual numerical calculation, how subtracting a suitably chosen number from every class mark and then dividing by a common factor can reduce the amount of arithmetic work while finding the arithmetic mean of the data. (iii) For the data given below, identify a convenient number that you would subtract from every class mark and state a suitable common factor you would divide by. Give one clear reason for each of your choices.| Electricity Consumed (units) | 90–110 | 110–130 | 130–150 | 150–170 | 170–190 | 190–210 |
|---|---|---|---|---|---|---|
| Number of households | 3 | 7 | 15 | 18 | 12 | 5 |