model 4 sold & brought Section-Wise Topic Notes With Detailed Explanation And Example Questions

Answer: (b)

S.P. of 7 pens = ${10 × 140}/100$ = Rs.14

S.P. of 1 pen = $14/7$ = Rs.2

Clearly, 5 pens were sold for Rs.10

Using Rule 13,

Here, a = 7, x = 10, b = ?, y = 10, Gain% = 40%

Gain% = $({ay - bx}/{bx})$ × 100%

40 = $({7 × 10 - b × 10}/{b × 10}) × 100%$

4b = 70 - 10b

14b = 70 ⇒ b = $70/14$ ⇒ b = 5

Answer: (b)

C.P. of 12 oranges = $60 × 100/75$ = Rs.80

For a gain of 25%,

S.P. of 12 oranges = ${80 × 125}/100$ = Rs.100

Hence, 12 Orange has to sell,

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Answer: (a)

Let the man buy 60 oranges (LCM of 20 and 30) of each kind. CP of the 60 oranges of the first kind

= $60/20 × 60$ = Rs.180

CP of 60 oranges of second kind $60/30 × 60$ = Rs.120

Total CP of 120 oranges = (180 + 120) = Rs.300

Their SP = $60/25 × 120$ = Rs.288

Loss = Rs.(300 - 288) = Rs.12

∴ Loss Per cent = $12/300 × 100$ = 4%

Answer: (a)

CP of Rs.100 cups = RS.100 × 10 = Rs.1000

10 cups are broken.

SP of 90 cups = Rs.(90 ×11) = Rs.990

Loss = Rs.(1000 - 990) = Rs.10

Loss per cent = $10/1000 × 100 = 1%$

Answer: (a)

C.P. of the tape recorder

= $100/95 × 950$ = Rs.1000

Gain = 1040 - 1000 = Rs.40

% Gain = $40/1000 × 100 = 4%$

Answer: (b)

Suppose, number of lemons bought

= LCM of 2, 5, 3 = 30

CP =Rs.$(1/2 × 30)$ = Rs.$15$

SP = Rs.$(3/5 × 30)$ = Rs.18

Gain = Rs.3; Gain per cent = $3/15 × 100 = 20%$

Using Rule 13,

Here, a = 2, x = 1, b = 5, y = 3

Gain% = $({ay - bx}/{bx})$ × 100%

= $({2 × 3 - 5 × 1}/{5 × 1}) × 100%$

= $1/5 × 100%$ = 20%