Interview Q&A / Aptitude

1. How do you calculate successive percentage changes?

   Two changes of a% and b% give a net change of a + b + (a x b) / 100 percent. Use negative values for decreases. For example, a 20% increase followed by a 20% decrease is a net 4% decrease, not zero.

   BeginnerIn-depth3 min read
2. How do you solve profit and loss questions with marked price and discount?

   Profit or loss percent is always calculated on the cost price. Discount percent is always calculated on the marked price. Chain them with multipliers. For example, mark up 25% and give 10% off, and the selling price is 1.25 x 0.9 = 1.125 times the cost, which is a 12.5% profit.

   BeginnerIn-depth4 min read
3. A student needs 40% to pass. She scores 178 marks and fails by 22 marks. What are the maximum marks?

   500. Pass marks = 178 + 22 = 200, and 200 is 40% of the maximum, so maximum = 200 / 0.40 = 500.

   BeginnerQuick answer1 min read
4. If A's salary is 20% more than B's, by what percentage is B's salary less than A's?

   B's salary is 16.67% (1/6) less than A's. If B earns 100, A earns 120. The gap of 20 is measured against A's 120: 20/120 = 1/6 = 16.67%.

   BeginnerQuick answer1 min read
5. If the price of sugar rises by 25%, by what percentage must a family cut its consumption to keep its spending the same?

   By 20%. Spending = price x quantity. If price becomes 125/100 of the old price, quantity must become 100/125 = 4/5, a cut of 1/5, which is 20%. Formula: r / (100 + r) x 100 = 25/125 x 100 = 20%.

   BeginnerQuick answer1 min read
6. In an election between two candidates, 20% of the 8,000 votes cast were invalid. The winner got 55% of the valid votes. How many valid votes did the loser get?

   2,880. Valid votes = 80% of 8,000 = 6,400. The loser got 100% - 55% = 45% of valid votes: 0.45 x 6,400 = 2,880. The winning margin is 10% of 6,400 = 640.

   BeginnerQuick answer1 min read
7. Ravi spends 75% of his income. His income rises by 20% and his spending by 10%. By what percentage do his savings increase?

   By 50%. Take income 100, spending 75, savings 25. New income 120, new spending 82.5, new savings 37.5. Increase = 12.5 on 25 = 50%.

   AdvancedQuick answer1 min read