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

Answer: (c)

According to the question,

$x × 10/100 = 3 × y × 15/100$

10x = 45y

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

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: (d)

Let C = 100; B = 80

A = ${80 × 160}/100 = 128$

A : C = 128 : 100 = 32 : 25

Answer: (b)

Let the number of boys and girls be 4x and x respectively.

Number of boys who hold scholarship. = $75/100 × 4x = 3x$

and number of girls who hold scholarship = ${70 × x}/100 = {7x}/10$

Number of students who do not hold scholarship

= $5x - 3x - {7x}/10 = 2x - {7x}/10$

= ${20x - 7x}/10 = {13x}/10$

The required percentage = ${{13x}/10}/{5x} × 100$

= ${13x}/{10 × 5x} × 100 = 26$%

Answer: (d)

Boys in school = 2x

Girls = 3x

Students who are not scholarship holders :

Boys ⇒ ${2x × 75}/100 = {6x}/4$

Girls ⇒ ${3x × 70}/100 = {21x}/10$

Total students who donot hold scholarship = ${6x}/4 + {21x}/10$

= ${30x + 42x}/20 = {72x}/20 = {18x}/5$

Required percentage = ${{18x}/5}/{5x} ×100$ = 72%

Answer: (d)

$x × 15/100 = y × 20/100$

x × 15 = y × 20

$x/y = 20/15 = 4/3$ = 4 : 3