Quantitative Aptitude - Arithmetic Ability Questions

Twenty one times of a positive number is less than its square by 100. The value of the positive number is

The difference between compound interest and simple interest on a certain sum of money for 2 years at 5% per annum is Rs. 41. What is the sum of money?

If x=aCosθCosΦ, y = aCosθSinΦ and z= aSinθ, then the value of x2+ y2 + z2 is

Find the value of 777777?

Which of the following is correct?

Working together, pipes A and B can fill an empty tank in 10 hours. They worked together for 4 hours and then B stopped and A continued filling the tank till it was full. It took a total of 13 hours to fill the tank. How long would it take A to fill the empty tank alone?

Yaman sold an item at a loss of 10%. If he had sold it for Rs.57 more, he would have made a profit of 20%. What should be the selling price of the item to make a profit of 30%?

If y=2-x1+x, then what is the value of 1y+1 + 2y+1y2-1 ?