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

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)

Let he buy 15 eggs. [LCM of 5 & 3]

CP of 15 eggs = Rs.25

SP of 15 eggs = Rs.36

Gain = 36 - 25 = Rs.11

Since, Rs.11 ≡ 15 eggs

Rs.143 ≡ $15/11$ × 143 = 195 eggs

Answer: (c)

Let the man buys 24 (LCM of 8 and 12) oranges.

C.P. of 24 oranges = $34/8 × 24$ = Rs.102

S.P. of 24 oranges = $57/12 × 24$ = Rs.114

Gain = 114 - 102 = Rs.12

Since, Rs.12 ≡ 24 oranges

Rs.45 ≡ $24/12 × 45$ = 90 oranges

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)

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,

[You can also check through options]

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