A trust caring for handicapped children gets Rs.30,000 every month from its donors. The trust spends half of the funds received for medical and educational care of the children and for that it charges2% of the spent amount from them , and deposits the balance amount in privatebank to get the money multiplied so that in future the trust goes on functioning regularly. What percent of interest should the trust get from the bank to get a total of Rs.1,800 every month?
Use matrix method, to find the rate of interest. Do you think people should donateto such trusts?

Here is the answer :

Out of Rs 30000, trust spends half for medical and educational care.So, amount deposited in Private bank = Rs 15000The trust charges 2% of the money spent  for medical and educational care.Earning of the trust from the above charges = 2% of Rs 15000 = Rs 300Let the earning of the trust from the above charges be Rs x and the earning from the interest obtained from the bank = Rs Ynow, X + Y = 1800X = 300The above equations in matrix form is,1110XY = 1800300XY = 1110-11800300XY =  0-1-11-11800300XY = 011-11800300XY = 3001500X = 300; Y = 1500Let the monthly rate of interest be R%Now, R% of Rs 15000 = Rs 1500R = 10

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