Page 293 - ICSE Math 8

PROFIT, LOSS, DISCOUNT AND TAX

Profit or Gain, when SP > CP Loss, when SP < CP
Profit = SP – CP, SP = Selling Price, CP = Cost Price Loss = CP – SP
 Profit   Loss
Profit % =   × 100 Loss % =   × 100
 CP   CP 

 100 + Profit % (100 × SP)  100 – Loss % (100 × SP)
SP =   × CP; CP = SP =   × CP; CP =
 100  (100 + Profit %)  100  (100 – Loss %)
Effective CP = CP + Overhead Expenses
Discount
SP = MP – Discount, MP = Marked Price  Discount 
Discount % =   × 100
 100 – Discount %  MP 
SP =   × MP
 100  100 × SP
MP =
(100 – Discount %)
Discount is always calculated on the marked price of an article.
Successive Discount: If D be the equivalent discount to two successive discounts D % and D %, then,
1
2
 D + D – (D × D )
D% =   1 2 100 1 2   %
Selling price after successive discounts of D , D , ..., D on the marked price (MP) is given by:
n
2
1
 D 1   D 2   D n 
S.P. = 1 −    1 −  …  1 −  × MP
 100   100   100 
Tax
(Rate of Tax × SP)  Tax 
Tax = or, Rate of Tax =   × 100%
100  SP 

PERIMETER AND AREA OF PLANE FIGURES

Polygon Area Perimeter Remarks
Rectangle 2 × (l + b) l × b l = Length, b = Breadth
Square a 2 4a a = side of square
Diagonal 2a
Triangle 1 a + b + c a, b, c = lengths of sides
2 × Base × Height s = a + b + c
Heron’s formula ( ss − a )(s − b )(s − ) c 2

Equilateral  3 
Triangle     a 2
 4 
Parallelogram Base × Height Sum of sides

1
Rhombus × Product of diagonals Sum of sides
2
Trapezium 1 Sum of sides a, b = length of parallel sides,
2 × (a + b) × h h = distance between them
Circle pr 2 2pr 22
2
Area of ring pR – pr 2 r = radius; p = 7

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