model 11 percentage with ratios Section-Wise Topic Notes With Detailed Explanation And Example Questions

Answer: (d)

Numbers ⇒ A and B

${A × 5}/100 + {B × 4}/100$

= $2/3({A × 6}/100 + {B × 8}/100)$

5A + 4B = ${12A + 16B}/3$

15A + 12B = 12A + 16B

15A – 12A = 16B – 12B

3A = 4B

$A/B = 4/3$ = 4 : 3

Answer: (b)

20 % of A = 30 % of B = $1/6$ of C

${20A}/100 = {30B}/100 = C/6$

$A/5 = B/{10/3} = C/6 = k (let)$

A = 5k, B = $10/3$k, C = 6 k

A : B : C = 5k : ${10k}/3$ : 6 k

= 15 : 10 : 18

Answer: (b)

C.P. of 1 litre of milk= Rs. 100

Mixture sold for Rs. 125

= $125/100 = 5/4$ litre

Quantity of water = $5/4 - 1 = 1/4$ litre

Required ratio = $1/4$ : 1 = 1 : 4

Answer: (d)

Let C = 100; B = 80

A = ${80 × 160}/100 = 128$

A : C = 128 : 100 = 32 : 25

Answer: (b)

Let the number of boys = 3x and that of girls = 2x

Number of boys who do not hold scholarship = 80% of 3x

= $3x × 80/100 = {12x}/5$

Number of girls who do not hold scholarship

= $2x × 70/100 = {14x}/10$

Number of students who do not hold scholarship

= ${12x}/5 + {14x}/10 = {24x + 14x}/10 = {38x}/10$

Required percentage = ${{38x}/10}/{5x} × 100 = 38/{10 × 5} × 100=76%$

Answer: (c)

According to the question,

$x × 10/100 = 3 × y × 15/100$

10x = 45y

$x/y = 45/10 = 9/2$