Page 182 - Start Up Mathematics_8 (Non CCE)

Ê 3 xˆ 23
\ Original S.P. = ` x + 20 ˜ ¯ = ` 20 x
Á
Ë
Ê 25 ˆ 3
New C.P. = (` x – 25% of ` x) = ` x - 100 x = ` 4 x
˜
Á
¯
Ë
Profit percent = 60%
Ê 100 + Profit% ˆ Ê 100 60+ ˆ 3x 160 3x 6
\ New S.P. = Á 100 ˜ ¯ ¥ C.P. = Á 100 ˜ ¯ ¥ 4 = 100 ¥ 4 = ` 5 x
Ë
Ë
According to the question, new S.P. is ` 20 more than the original S.P.
\ New S.P. = Original S.P. + ` 20

fi New S.P. – Original S.P. = 20
6 23 24x - 23x
fi x - x = 20 fi = 20
5 20 20
x
fi = 20 fi x = 400
20
Hence, C.P. of the pen drive = ` 400
Example 9: By selling 33 oranges, a fruit seller gains the selling price of 11 oranges. Find the profit
percent.
Solution: Profit = S.P. of 33 oranges – C.P. of 33 oranges

fi S.P. of 11 oranges = S.P. of 33 oranges – C.P. of 33 oranges
fi C.P. of 33 oranges = S.P. of 33 oranges – S.P. of 11 oranges
fi C.P. of 33 oranges = S.P. of 22 oranges
Let the C.P. of 1 orange = ` 1
\ C.P. of 33 oranges = ` 33 = S.P. of 22 oranges

fi S.P. of 22 oranges = ` 33
33 3
fi S.P. of 1 orange = ` = `
22 2
Ê 3 ˆ 1
Profit = S.P. of 1 orange – C.P. of 1 orange = ` Á Ë 2 - 1 ˜ = ` 2
¯
1
Profit 2 1
\ Profit % = × 100 = ¥ 100 = × 100 = 50%
C.P. 1 2
\ Profit % = 50%
Example 10: Honey sold a wrist watch to Kirti at 20% profit. Kirti further sold it to Muskan at a profit of
5%. If Muskan paid ` 441 for it, what was the cost price of the wrist watch?

Solution: Let the cost price of the wrist watch be ` x.
Honey’s profit% = 20%

S.P. for Honey = Ê Á Ë 100 + Profit%ˆ ˜ ¯ C.P.¥ = ` Ê Á Ë 100 20+ ˆ ˜ ¯ ¥ x = ` 120 x = ` 6 x
5
100
100
100
6
S.P. for Honey = C.P. for Kirti = ` x
5
Kirti’s profit = 5%
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