Page 96 - Maths Skills - 7

94 Maths

Solution: (i) We have, C.P. = ` 790 and S.P. = ` 870 (ii) We have, C.P. = ` 650 and S.P. = ` 610
Clearly, S.P. > C.P. Clearly, C.P. > S.P.
Profit = S.P. – C.P. Loss = C.P. – S.P.

= ` (870 – 790) = ` 80 = ` (650 – 610) = ` 40
Profit Loss
Therefore, profit per cent = C.P. × 100 Therefore, loss per cent = C. P. × 100

= 80 × 100 = 40 × 100

790 650
800 10 80 2
= = 10 = = 6
79 79 13 13

So, profit% = 10 10 %. 2
79 So, loss% = 6 13 %.

Type II: Finding S.P. when C.P. and Profit or Loss Per Cent are Given

Example 4: A shopkeeper buys room-coolers at ` 5500 each. On account of slump in the market he is forced
to sell them at 12% loss. Find the selling price of each room-cooler.

Solution: Loss = 12% of ` 5500 = 12 × ` 5500 = ` 660
100
Loss = C.P. – S.P.
Or, S.P. = C.P. – Loss

= ` (5500 – 660) = ` 4840
\ The S.P. of each room-cooler is ` 4840.

Example 5: An article costs ` 425 and is sold at a profit of 15%. Find the S.P.
15
Solution: Profit = 15% of ` 425 = 100 × ` 425 = ` 63.75
Profit = S.P. – C.P.
Or, S.P. = C.P. + Profit
Or, S.P. = ` 425 + ` 63.75 = ` 488.75.

Type III: Finding C.P. when S.P. and Profit or Loss Per Cent are Given

Example 6: By selling a table for ` 360, a trader loses 10%. Find the cost price of the table.

Solution: S.P. of a table = ` 360, loss = 10% Fact-o-meter

Therefore, C.P. = S.P. × 100 Formulae to find Selling Price and Cost Price:
(100 – loss%) C.P. × (100 + gain%)
� If there is a gain%, S.P. = 100
= ` 360 × 100
(100 – 10) � If there is a loss%, S.P. = C.P. × (100 – loss%)

= ` 36000 100
90 � If there is a gain %, C.P. = S.P. × 100

= ` 400.00 (100 + gain%)
S.P. × 100
� If there is a loss %, C.P. =
\ The cost price of a table is ` 400. (100 – loss%)