### Ex. No. 1

1. The ratio of number of boys and girls in a school is 3:2. If 20% of the boys and 30% of the girls are scholarship holders, find the percentage of students who are not scholarship holders.[video]

2. If the numerator of a fraction is increased by 20% and its denominator be diminished by 10%, the value of the fraction is 16/21, find the original fraction. [video]

3. The ratio of incomes of Salim and Jawed was 20:11. Three years later income of Salim has increased by 20% and income of Jawed was increased by Rs. 500. Now ratio of their incomes becomes 3:2. Find original incomes of Salim and Jawed.[video]

4. In a class, 60% students are boys and 40% are girls. By admitting 16 boys and 8 girls the ratio of boys to girls becomes 8:5. What must be the number of boys and number of girls originally in the class? [video]

5. Incomes of Mr. Shah, Mr. Patel and Mr. Mehta are in the ratio 1:2:3; while their expenditure are in the ratio 2:3:4. If Mr. Shah saves 20% of his income, find the ratio of their savings. [video]

6. What must be subtracted from each of the numbers 5, 7 and 10, so that the resulting numbers are in the continued proportion? [video]

7. The employees of a firm have maintained their standard of living in such a manner, that they all have identical percentage of saving from their salaries. Amina and Sabina are two employees of the firm. Amina spends Rs. 12,800 per month from her salary of Rs. 35,000 per month. What would be Sabina's savings per month from her salary of Rs. 48,000 per month? [video]

8. A certain job can be performed by 10 men in 24 days working 8 hours a day, How may days would be needed to perform the same job by 8 men working 12 hours a day? [video]

9. Two metals X and Y are to be used for making two different alloys. If the ratio by weight of X:Y in the first alloy is 6:5 and that in the second is 7:13. How many kg of X metal must be melted along with 11 kg of the first alloy and 20 kg of second alloy so as to produce a new alloy containing 40% of metal Y? [video]

10.Three persons A, B and C whose salaries together amount to Rs. 21,000. Their savings are 20%, 30% and 40% of their salaries respectively. If their expenditures are in the ratio 8:14:3, find their respective salaries. [video]