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

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: (b)

Let the vendor buy 20 (LCM of 5 and 4) bananas.

CP of 20 bananas = Rs.4

SP of 20 bananas = Rs.5

Gain% = ${5 - 4}/4 × 100 = 25%$

Using Rule 13,

Here, a = 5, x = 1, b = 4, y = 1

His gain%= $({ay - bx}/{bx})$ × 100%

= $({5 × 1 - 4 × 1}/{4 × 1}) × 100%$

= $1/4$ × 100% = 25%

Answer: (b)

If the CP of 20 apples be Rs.x,

then ${x × 120}/100 = 100$

$x = {100 × 100}/120$ = Rs.$250/3$

Rs.$250/3$ = 20 apples

Rs.100 = ${20 × 3 × 100}/250$ = 24 apples

Using Rule 13,

Here, a = ?, x = 100, b = 20, y = 100, Gain% = 20%

Gain% = $({ay - bx}/{bx})$ × 100%

20% = $({a × 100 - 20 × 100}/{20 × 100}) × 100%$

400 = 100a - 2000

2400 = 100a ⇒ a = 24

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: (c)

Using Rule 1,

Let the SP of 1 book = x

SP of 25 books = 25x

According to the question,

25x - 2000 = 5x

20x = 2000 ⇒ x = $2000/20$ = 100

SP of 1 book = Rs.100

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 = $10/1000 × 100 = 1%$