$$ {{2^n+2^{n-1}}\over {2^{n+1} -2^n}}=?$$

A vendor sells potatoes at a cost price, but he mixes some rotten potatoes and thereby gains 25%. The percentage of rotten potatoes in the mixture is? 

A conical vessel whose internal base radius is 18 cm and height 60 cm is full of a liquid. The entire liquid of the vessel is emptied into a cylindrical vessel with internal radius 15 cm. The height (in cm) to which the liquid rises in the cylindrical vessel is:

The HCF of two numbers is 4 and the two other factors of LCM are 5 and 7. Find the smaller of the two numbers.

A family has two grandparents, two parents and four children. Two years ago, the average age of grandparents was 72 years. A year ago, the average age of parents was 36 years. Currently, the average age of children is 12 years. What is the current average age of the family?

Two years ago, the average age of Aman and Shyam was 26 years. Five years hence, the age of Aman will be 40 years and Shyam is 5 years younger than Mohan, then find the difference between the age of Aman and Mohan.

₹12,000 is lent for one year t the rate of 15% per annum, the interest being compounded annually. If the compounding of the interest is done half- yearly, then how much more interest will be obtained at the end of the one-year period on the same initial sum?

The value of a mobile phone depreciates at the rate of 10% every year. It was purchased 3 years ago. If its present value is Rs. 6561/-, its purchase price was.