The lifetimes (in hours) of 120 electric bulbs produced by a factory are recorded below
MATHEMATICS · Multi-part · CBSE · Mathematics · Statistics · Statistics
Problem
The lifetimes (in hours) of 120 electric bulbs produced by a factory are recorded below. Notice that the class sizes are not all the same. (a) Draw up a working table with any columns you find necessary to calculate the arithmetic mean of the lifetimes.| Lifetime (hours) | 200–300 | 300–400 | 400–450 | 450–500 | 500–600 |
|---|---|---|---|---|---|
| Number of bulbs | 8 | 30 | 25 | 37 | 20 |