Question

33. The boys and girls are in the ratio 3:2. If 10% of the boys and 25% of the girls are brilliant, the percentage of students NOT brilliant is:​

Answer 1

Step-by-step explanation:

let total students be 100

A/Q-

3x+2x=100

5x=100

x=20

no. of girls = 2x = 40

no. of brilliant girls = 25% = 40 × 25/100 = 10 girls

no. of boys = 3x = 60

no. of brilliant boys = 60 × 10/100 = 6

total brilliant students = 16 students

percentage of total brilliant students =

16/100 × 100 = 16%

Answer 2

Answer:

The percentage of students NOT brilliant is 84%.

Given:

Ratio of boys and girls = 3:2

brilliant boys = 10%

brilliant girls = 25%

To find:

percentage of  NOT brilliant students.

Step-by-step explanation:

It is given that,

The boys and girls are in the ratio 3:2.

So, let us take number of boys be 3x and number of girls be 2x.

Number of students will be 3x + 2x = 5x.

10% of the boys are brilliant

so, 10% of 3x will be

$3x * \frac{10}{100} = \frac{3x}{10}$

and 25% of the girls are brilliant

so, 25% of 2x will be

$2x * \frac{25}{100} = \frac{x}{2}$

Total number of brilliant students = $\frac{3x}{10} + \frac{x}{2} = \frac{3x + 5x}{10} = \frac{8x}{10} =\frac{4x}{5}$

Total number of non brilliant students = $5x -\frac{4x}{5} = \frac{25x-4x}{5} = \frac{21x}{5}$

percentage of non brilliant students =

$= \frac{\frac{21x}{5} }{5x} * 100\\ = \frac{21x}{25x} * 100\\= 21 * 4\\= 84$

Hence, the percentage of students NOT brilliant is 84%.

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