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  1. LPU MCA Semester 1
  2. PEA515
  3. Unit 2

PEA515 · Unit 2: Percentage and profit and loss

Discount, faulty weight, number of articles and common selling price

30 practice questions · in the MTE and ETE syllabus

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Key points

  • Equivalent discount = d1 + d2 - d1 d2/100
  • Faulty weight gain divides by the weight given
  • Equal selling price with equal gain and loss means a loss of g squared over 100 percent
  • Cost of x = selling price of y gives (x - y)/y

Successive discounts d1% and d2% equal a single discount of d1 + d2 - d1 d2 / 100. Discounts of 20% and 10% give 20 + 10 - 2 = 28%.

Mark-up then discount: a mark-up of m% followed by a discount of d% gives a net change of m - d - m d / 100.

Faulty weight: a seller who uses a weight of w grams for 1000 g, selling at cost price, gains (1000 - w) / w x 100 percent. Using 950 g gives 50/950 x 100 = 5.26%.

Number of articles: if the cost of x articles equals the selling price of y articles, then profit% = (x - y)/y x 100.

Common selling price: if two items are sold at the same price, one at a gain of g% and the other at a loss of g%, the overall result is always a loss of g^2/100 percent.

Exam trap: dividing the faulty-weight shortfall by 1000 instead of by the weight actually given.

Try two questions

Question 1 · Tier 4, Analyse

A shop gives successive discounts of 12%, 25% and 40% on a pen set. What single discount is equivalent?

  1. 77%
  2. 25.67%
  3. 65.2%
  4. 60.4%
Show the answer

D. Multiply the retained fractions 22/25 x 3/4 x 3/5 and subtract the product from 1.

Why not A: Adds the discounts directly; successive discounts apply to a reduced price.

Why not B: Averages the discounts instead of compounding them.

Why not C: Adds the cross-term where it should be subtracted.

Question 2 · Tier 3, Apply

A dishonest shopkeeper sells goods at cost price but uses a weight of 850 g in place of 1 kg. Find the gain percent.

  1. 15%
  2. 82.35%
  3. 85%
  4. 17.65%
Show the answer

D. The customer pays for 1000 g but receives 850 g, so gain = (1000 - 850) / 850 x 100.

Why not A: Divides the shortfall by 1000 g instead of by the weight actually given.

Why not B: Mixes up the direction of the difference.

Why not C: Reports the weight as a percentage of a kilogram.