**1.**There is an 8 liters cylinder a mixture of Nitrogen and Oxygen, the volume of Oxygen being 16%of the total volume. A few liters of the mixture are released and an equal amount of Nitrogen is added. Then the same amount of the mixture as before is released and replaced by the nitrogen for the second time. As a result, the Oxygen content becomes 9% of the total volume. How many liters of mixture are released each time?

**2.**A scooter costs Rs 25,000 when it is brand new. At the end of each year, its value is only 80% of what it was the previous year. What is the value of the scooter at the end of the 3 years?

**3.**The population of bacteria culture doubles every 2 minutes. Approximately, how many minutes will it take for the population to grow from 1000 to 500,000 bacteria?

**4.**The length and width of a rectangular garden are increased by 20 %. What is the increase in Area?

**5.**In a class 40% of the boys are equal to ½ the girls, and the number of girls are 20. So, the total number of students in the class is?

**6.**40% of the students in a college play basketball, 34% of the students play tennis and the number of students who play both the games is 234. The number of students who play neither basket ball nor tennis is 52%.Determine the student population of the college.

**7.**There are five boxes in a cargo hold. The weight of the first box is 200kg and the weight of the second box is 20% higher than the weight of the third box, whose weight is 25% higher than the first box. The fourth box at 350kg is 30% higher than the 5

^{th}box. The difference in average weight of the four heaviest boxes and the four lightest boxes is?

**8.**A vendor bought toffees at 6 for a rupee. How many for a rupee must he sell to gain 20%?

**9.**A shopkeeper expects a gain of 22.5% on his cost price. If in a week his sale was Rs.392, what was his profit?

**10.**Some apples were bought at 6 apples for Rs.5 and subsequently sold at 5 articles for Rs.6. Gain percent is :

**11.**On selling 17 balls at Rs.720, there is a loss equal to the cost price of 5 balls. The cost price of a ball is :

**12.**100 oranges are bought at the rate of Rs.350 and sold at the rate of Rs.48 per dozen. What is the percentage profit or loss?

**13.**A trader mixes 26kg of rice at Rs.20/kg with 30 kg of rice of other variety at Rs. 36/kg and sells the mixture at Rs.30/kg. His profit percent is :

**14.**If the selling price is doubled, the profit triples. Find the profit percent.

**15.**In a certain store, the profit is 320% of the cost. If the cost increases by 25% but the selling price remains constant, approximately what percentage of the selling price is the profit?

**16.**Akshay bought 20 dozens of bananas at the rate of Rs. 375 per dozen. He sold each dozen at the rate of Rs.33. What was his percentage profit?

**17.**If cost price is 96% of the selling price, then what is the profit percent?

**18.**If an article is sold at 5% gain instead of 5% loss ,the seller gets Rs.6.72. The C.P of the article is?

**19.**Keshav bought paper sheets for Rs. 7200 and spent Rs.200 on transport. Paying Rs.600, he had 330 boxes made, which he sold at Rs.28 each. What is his profit percentage?

**20.**A dishonest shopkeeper sells goods at a price 6.25% less than the cost price but uses 12.5% less weight. What is his profit percent?

**21.**If the manufacturer gains 10%,the wholesale dealer 15% and the retailer 25% ,then find the cost of production of a ,the retail price of which is Rs.1265?

**22.**An article is sold at a certain price , by selling it at 2/3 of its price , a kirana store owner loses 10%. Find the gain at original price .

**23.**A man sold ¾ of his articles at a gain of 20% , and remaining at a cost price. Find the total gained by him , in the course of these two transaction .

**24.**Pranav bought a sketchpad ,for his cartoons , at 9/10

^{th}of its selling price , and sold it at 8% more than its Selling Price. Now , he goes back home and wants to know his profit percent. What is it ?

**25.**Saffron ,miraculously , at a place costs Rs. 100 /kg. After adulterating it with some substance which costs Rs.50/kg. A shopkeeper sells the mixture at the rate of Rs.96/kg , thereby making a profit of 20%. In what ratio , does he mix the two ?