Arithmetic Mean
Sum of all items divided by the number of items.
Average = Sum / Count
Quantitative Aptitude
Averages represent the central value of a dataset. Master average calculations, group additions/removals, replacements, and weighted averages.
An average is the total of a set divided by the count, but aptitude questions rarely ask the formula directly. The standard patterns are: finding a missing number from the average, what happens when items are added, removed or replaced, combined group averages, and weighted averages. Every one of these is solved by first converting the average back into a total.
The average or arithmetic mean is the sum of values divided by the count.
Sum of all items divided by the number of items.
Average of multiple groups combined.
Recover the total value when average and count are known.
The recurring question patterns in this topic — know the shape of each pattern before you solve.
Given the average and all elements except one, find the missing value.
Avg 5 numbers = 24; four are known → fifth = total − sum of four.
The average changes when an element is added or removed; work in totals.
Student of weight 50 kg replaced → average drops 40 → 38.
Two groups with different averages merge; find overall average.
30 girls avg 60 + 20 boys avg 75 → combined 66.
Values with weights; compute weighted sum divided by total weight.
Marks weighted by section sizes.
Average of consecutive numbers equals the middle value.
First 7 odd numbers avg = 7th position value 3+2×(7−1)/... = 9.
High-signal questions with full solution flow across difficulty patterns.
Classic exam problems worth internalizing — each one ships a complete step-by-step solution.
Quickly find the value of a new group member.
Where most students lose marks — review these before you sit the test.
You have mastered the theory. Now put it under pressure with a focused topic test and instant explanations.
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