Question

Three generous friends, each with some money, redistribute the money as follows: sandra gives enough money to david and mary to double the amount of money each has. David then gives enough to sandra and mary to double their amounts. Finally, mary gives enough to sandra and david to double their amounts. If mary had 11 rupees at the beginning and 17 rupees at the end, what is the total amount that all three friends have?

Answer 1

The answer is 71 rupees.

Mary had initially 11 rupees.

In the first step, Sandra gives enough money to double it. So Sandra gives 11 rupees, so now nary has 11 + 11 = 22 rupees.

In the second step, David gives enough money to double it. He must have given 22 rupees. So now Mary has 22 + 22 = 44 rupees.

In the third step, Mary gives money to double the amount of David and Sandra and she is having, only rupees 17 as balance.

44 - 17 = 27

So she has given 27 rupees totally to both Sandra and David. That means before the third step, Sandra and David together both had 27 rupees. and before the third step, Mary had 44 rupees. So the total amount that all three friends have is  

44 + 27 = 71 rupees