The boys and girls in a college are in the ratio 3 : 2. If 20% of the boys and 25% of the girls are adults, the percentage of students who are not adults is -
A. 67.5%
B. 58%
C. 78%
D. 82.5%
Answer: Option C
Solution(By Examveda Team)
Let the number of boys and girls be 3x and 2x respectivelyThen,
Number of boys and girls who are adults
$$\eqalign{ & = 20\% {\text{ of }}3x + 25\% {\text{ of }}2x \cr & = \left( {\frac{{20}}{{100}} \times 3x} \right) + \left( {\frac{{25}}{{100}} \times 2x} \right) \cr & = \frac{3}{5}x + \frac{x}{2} = \frac{{11x}}{{10}} \cr} $$
∴ Number of boys and girls who are not adults
$$\eqalign{ & = \left[ {\left( {3x + 2x} \right) - \frac{{11x}}{{10}}} \right] \cr & = 5x - \frac{{11x}}{{10}} \cr & = \frac{{39x}}{{10}} \cr & {\text{Required percentage}} \cr & = \left( {\frac{{39x}}{{10}} \times \frac{1}{{5x}} \times 100} \right)\% \cr & = 78\% \cr} $$
Related Questions on Ratio
If a : b : c = 3 : 4 : 7, then the ratio (a + b + c) : c is equal to
A. 2 : 1
B. 14 : 3
C. 7 : 2
D. 1 : 2
If $$\frac{2}{3}$$ of A=75% of B = 0.6 of C, then A : B : C is
A. 2 : 3 : 3
B. 3 : 4 : 5
C. 4 : 5 : 6
D. 9 : 8 : 10
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