Quantitative Aptitude - Arithmetic Ability Questions

In a class of 60 students there are 30 girls. The average weight of these girls is 58 Kg and average weight of the full class is 63 kgs. What is the average weight of the boys of the class?

If a2b+c=b2C+a=a2a+b=1 then 11+a+11+b+11+c is

A shopkeeper cheats to the extent of 11% while buying and selling fruits, by using tampered weights. His total gain in percentage is

If a dairy mixes cow's milk which contains 10% fat with buffalo's milk which contains 20% fat, then the resulting mixture has fat (120/7)% of fat. What ratio was the cow's milk mixed with buffalo's milk?

If a - b = 10 and ab =-21, then what is the value of a3-b3 ?

If a/b = c/d = e/f = 2/5, then what is (5a + 3c + 2e) : (5b + 3d + 2f)?

Slope of the side DA of the rectangle ABCD is 5/3. What is the slope of the side AB?

A vendor buys bananas at 12 for Rs 50 and sells at 5 for Rs 40. What will be the gain (in %)?