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

Answer: (a)

Let the person buy 10 articles.

Total CP = Rs.$(1 + 5/4)$ = Rs.$9/4$

SP of 10 articles = Rs.$2/9 × 10$ = Rs.$20/9$

Loss = Rs.$(9/4 - 20/9)$ = Rs.$({81 - 80}/36)$ = Rs.$1/36$

Now, if loss is Rs.$1/36$, number of articles = 10

If loss is Rs.3, number of articles = 36 × 10 × 3 = 1080

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%

= $({6 × 6 - 4 × 4}/{4 × 4}) × 100%$

= $({36 - 16}/16) × 100%$

= $20/16 × 100% = 125%$

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 CP of each ball = x.

Then, clearly the cost price of (17 - 5) balls = Rs.720

i.e., 12x = 720 ⇒ x = 60 i.e. Rs.60

Answer: (d)

Using Rule 2,

Total actual C.P. = Rs.(500 × 10 + 2000) = Rs.7000

And total S.P. = Rs.(5 × 750 + 5× 550)

= Rs.(3750 + 2750) = Rs.6500

Loss = 7000 - 6500 = Rs.500

Loss percent = $500/7000 × 100 = 50/7 = 7{1}7%$

Answer: (d)

Let number of articles bought = 6 × 5 = 30

C.P. of 30 articles = Rs.$(5/6 × 30)$ = Rs.25

S.P. of 30 articles = Rs.$(6/5 × 30)$ = Rs.36

Gain % = ${36 - 25}/25 × 100$ = 44%

Using Rule 13,

Here, a = 6, x = 5, b = 5, y = 6

Gain% = $({ay - bx}/{bx})$ × 100%

= $({6 × 6 - 5 × 5}/{5 × 5})$ × 100%

= $({36 - 25}/25) × 100% = 11/25 ×100%$ = 44%