In a particular week, the average earning per day of a plumber from Monday to Wednesday remained ₹580 and that from Thursday to Saturday it was ₹612. If the average earning for the whole week was ₹675, then how much did he earn on Sunday?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → ₹1149
An average multiplied by the number of days gives the total earning of those days; Sunday’s earning is what is left of the week’s total.
Whole week (7 days) \(=7\times675=4725\)
Monday to Wednesday \(=3\times580=1740\)
Thursday to Saturday \(=3\times612=1836\)
Sunday \(=4725-1740-1836=\) ₹1149
Shortcut: Measure every day from the weekly average of ₹675.
Monday to Wednesday: each ₹95 below, a total of ₹285 below
Thursday to Saturday: each ₹63 below, a total of ₹189 below
Sunday must make up \(285+189=474\) above the average: \(675+474=\) ₹1149