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

Answer: (d)

C.P. of 50 pens = 50 × 50 = Rs.2500

For profit of 10%,

S.P. = ${2500 × 110}/100$ = Rs.2750

S.P. of 40 pens at a loss of 5%

= ${40 × 50 × 95}/{100}$ = Rs.1900

S.P. of remaining 10 pens = 2750 - 1900 = Rs.850

Gain % = ${850 - 500}/500 × 100$ = 70 %

Answer: (c)

Loss = 5 - 4.50 = 0.50

Loss percent = ${0.50}/5 × 100$ = 10%

Using Rule 13,

Here, a = b, x = 5a, y = 4.50a

Loss % = $({ay - bx}/{bx})$ × 100%

= $({4.50a^2 - 5a^2}/{5a^2})$ × 100%

= $({-0.5a^2}/{5a^2})$ × 100%

= 10% (–ve sign shows loss)

Answer: (c)

Using Rule 1,

Let the CP of each watch be x.

CP of 14 watches = 14x

and SP of 14 watches = Rs.6300

According to the question,

6300 - 14x = 4x

18x = 6300 ⇒ x = $6300/18$ = Rs.350

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: (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 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%