Two numbers are in the ratio x : y . If 2 is added to both numerator and denominator ,  the fraction becomes $$ 1\over2$$. Find the value of x + y . 

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In a college there are 900 students who are doing Post Graduation (PG) in any one of the subjects, out of five different subjects, out of the five different subjects viz. Zoology, Botany, Mathematics, Physics and Statistics. The ratio between the boys and the girls among those is 5:4 respectively, 20% of the total girls are doing PG in Zoology and 25% of the total girls are doing PG in Statistics. Total number of students doing PG in Botany is 220. Total students who are doing PG in Mathematics is 150. Respectively ratio between the number of girls and the number of boys doing PG in statistics is 2:3. Twenty percent of the total number of boys are doing PG in Mathematics is 1:2 respectively. There are equal number of boys and girls who are doing PG in PG in Physics. 180 students are doing PG in Zoology.
What is the total number of students during PG in Physics and Statistics together?

A cistern can be filled by two pipes A and B in 4 hours and 6 hours respectively. When full, the tank can be emptied by a third pipe C in 8 hours. If all the taps be turned on at the same time, the cistern will be full in 

Two casks of 48 liter and 42 liter are filled with mixtures of milk and water, the proportions in the two casks being respectively 13 : 7 and 18 : 17. If the contents of two casks be mixed and 20 liter of water be added to the whole , what will be the proportion of milk and water in the resulting mixture ?

The numerator of a fraction is multiple of two numbers. One of the numbers is greater than the other by 2. The greater number is smaller than the denominator by 4. If the denominator 7 + C ( C > - 7 ) is a constant, then the minimum value of the fraction is :

A positive integer when divided by 425 gives remainder 45. When the same number is divided by 17, the remainder will be 

A scientific calculator is available at universal shoppe in hazratganj at 20 % discount and the same is available at only 15 % discount of universal shoppe Bhootnath market. Mr. Agrawal has just sufficient amount of 800 to purchase it at universal shoppe hazratganz. What is the amount that Mr. Agrawal has less than the required to purchase it at universal. shoppe Bhootnath ?