13 questions from actual SSC GD Constable papers · all shown free · click option to reveal solution
Percentage word problems involve finding parts of a whole, comparing quantities, or calculating increases and decreases in real scenarios like salary hikes, discounts, population growth, and election results
Always identify the base value first. The base is usually mentioned after 'of' or 'than'. When percentage increases, new value = original + increase. When percentage decreases, new value = original - decrease.
In comparison problems, identify which quantity is 100%.
SSC CGL typically asks about salary changes, price variations, population problems, election results, and mixture problems. Questions often involve successive percentage changes or finding original values when final values are given. Powerful Shortcut - The 'Of-Is' Method: In any percentage problem, identify the 'OF' value (base/whole) and 'IS' value (part). Then use: Percentage = (IS/OF) × 100. This works for all percentage word problems.
Let original salary = x
After 20% increase = x × 120/100 = 1.2x
After 15% decrease = 1.2x × 85/100 = 1.02x
Given final salary = 10,200
So, 1.02x = 10,200
x = 10,200/1.02 = 10,000 Therefore, original salary = Rs. 10,000 Another Shortcut: For successive percentage changes, if there are a% increase followed by b% decrease, net effect = [a - b - (ab/100)]%. If positive, it's increase; if negative, it's decrease. Using this shortcut: Net effect = 20 - 15 - (20×15/100) = 5 - 3 = 2% increase So final salary = original × 1.02 = 10,200 Original = 10,200/1.02 = 10,000
Students often confuse the base value. Remember, percentages are always calculated on the original or given base value, not on intermediate results unless specifically mentioned.