Two pipes P and Q would fill a cistern in 24 hours and 32 hours respectively. If both pipes are opened together, find when the pipe “P” must be turned off so that the cistern may be just filled in 16 hours-

The difference between the simple interest and the compound interest on a certain amount at 5% for two years is 25, what is the amount?

What is the difference (in ₹) between the simple interest and the compound interest on a sum of ₹8000 for $$32{2\over 5}$$ years at the rate of 10% p.a., when the interest is compounded yearly?

if x⁴+y⁴+x²y²=21 and x²+y²-xy=7, then what is the value of  $${x\over y}+{y\over x}=?$$

The simple interest on a sum for 5 years is one fourth of the sum. The rate of interest per annum is

Six years ago, the ratio of the ages of Karn and Sahil was 6 : 5. Four years hence, the ratio of their ages will be 11 : 10. What is Sahil’s age at present?

While selling a cooler, a shopkeeper gives a discount of 10% on the marked price. If he gives a discount of 12% he earns ₹ 35 less as profit. The marked price of the cooler is 

A certain number of students from school X appeared in an examination and 30% students failed. 150% more students than those from school X, appeared in the same examination from school Y. If 80% of the total number of students who appeared from X and Y passed, then what is the percentage of students who failed from Y?