Quantitative Aptitude - Arithmetic Ability Questions

Mansukh can do a piece of work in 10 hours. If he is joined by Jayanti who is 50% more efficient, in what time will they together finish the work?

What is the rate of interest (in %) if simple interest earned on a certain sum for the 3 years is Rs 6,000 and compound interest earned for 2 years is Rs 4,160?

If a wholesaler, sells a tin of coffee at Rs 528 he faces a loss of 12%. Now if he decides to sell it at Rs 636, what will be the profit (in %)?

The ratio of number of boys and girls in a class is 2 : 3. The average weight of boys and girls in the class is 18 kg and 21 kg respectively. What is the average weight (in kgs) of all the boys and girls together?

The standard deviation of the set {10, 11, 9, 11, 9} is

P and Q are two alloys which are prepared by mixing tin and lead in the ratio of 12 : 5 and 4 : 3 respectively. If equal quantities of alloys are melted to form athird alloy R, then what is the ratio of tin and lead in alloy R?

Ravi invested Rs.P in a scheme A offering simple interest at 10% p.a. for two years. He invested the whole amount he received from scheme A, in another scheme (B) offering simple interest at 12% p.a. for five years. If the difference between the interests earned from schemes A and B was Rs. 13,00/, what is the value of P ?

P and Q can do a project in 150 and 100 days respectively. In how many days can they complete 60% of the project if they work together?