Quantitative Aptitude - Arithmetic Ability Questions

On decreasing the price of a fan by 40%, its sales increases by 50%. What will be the percentage increase or decrease in its revenue?

The price of an article is decreased by 10%. To restore it to its former value, the new price must be increased by

Manish, Mukesh and Sachin are Accountants. Mukesh can filea return in 5 hours and Sachin in 4 hours alone. All three together can do it in 2 hours. In what time (in hrs) will Manish do the work?

When a number is increased by 120, it becomes 130% of itself. What is the number?

Rs 11,550 has to be divided between X, Y & Z such that X gets 4/5 of what Y gets and Y gets 2/3 of what Z gets. How much more does Z get over X (in Rs)?

A student multiplied a number by 6/7 instead of 7/6. What is the percentage error in the calculation?

If 9x - [5(2x + 1)/2] = 9/2, then the value of x is?

If x + y = 10 and x2 + y2 = 68, then find xy