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

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: (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: (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)

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%

Answer: (d)

Let Ravi buy 10 toffees.

C.P. = Rs.5; S.P. = Rs.2

Loss % = ${5 - 2}/5 × 100$ = 60%

Using Rule: 13

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

Loss % = $({ay - bx}/{bx})$ × 100%

= $({2 × 1 - 5 × 1}/{5 × 1}) × 100%$

=${-3}/5 × 100%$

= 60% (-ve sign shows loss)

Answer: (b)

Let the number of pencils bought = LCM of 4, 6 = 12

CP of 6 pencils = Rs.4

CP of 12 pencils = Rs.8

S.P. of 4 pencils = Rs.6

S.P. of 12 pencils = Rs.18

Profit = Rs. (18 - 8) = Rs.10

Profit % = $10/8 × 100 = 125%$

Using Rule: 13

Here, a = 6, x = 4, b = 4, y = 6

Gain% = $({ay - bx}/{bx})$ × 100%

= $({6 × 6 - 4 × 4}/{4 × 4}) × 100%$

= $({36 - 16}/16) × 100%$

= $20/16 × 100% = 125%$