Table – Daily Wages of 5 Workers Over 4 Days The table below shows the daily…

Concept: The average (arithmetic mean) of a set of values is their sum divided by how many values there are: mean = (sum of the values) ÷ (number of values). When an average daily amount is asked for over a stated period, the period fixes both parts of that fraction — the sum runs over every day of the period, each day counted exactly once, and the divisor is the number of days in the period, never the number of entries one happens to pick out.

Application: Read the required row of figures out of the table, then apply the definition.

1. Locate the Worker C column and read its entry for each of the four days: Day 1 = 220, Day 2 = 230, Day 3 = 215, Day 4 = 225.

2. Add the four entries: 220 + 230 = 450, then 450 + 215 = 665, then 665 + 225 = 890. So Worker C earns a total of 890 across the four days.

3. The period is 4 days long, so divide the total by 4: 890 ÷ 4 = 222.5.

4. The average daily earning of Worker C is therefore 222.5.

Cross-check: Two independent checks agree with 222.5.

• Deviation method: take 220 as a working base. The deviations of 220, 230, 215 and 225 from that base are 0, +10, −5 and +5, which total +10. The average deviation is +10 ÷ 4 = +2.5, so the mean is 220 + 2.5 = 222.5.

• Range check: a mean must lie between the smallest and the largest value of the set. Worker C’s entries run from 215 to 230, and 222.5 lies inside that range.

Contrast: Each of the other offered values comes from a different arithmetic operation on the same column.