One solved questions from CBSE Class 12th Mathematics Solved Question Paper (Set-1) are given here
Q. The management committee of a residential colony decided to award some of its members (say x) for honesty, some (say y) for helping others and some others (say z) for supervising the workers to keep the colony neat and clean. The sum of all the awardees is 12. Three times the sum of awardees for cooperation and supervision added to two times the number of awardees for honesty is 33. If the sum of the number of awardees for honesty and supervision is twice the number of awardees for helping others, using matrix method, find the number of awardees of each category. Apart from these values, namely, honesty, cooperation and supervision, suggest one more value which the management of the colony must include for awards.
Let the awardees for honesty = x
Let the awardees for helping others = y
Let the awardees for keeping the colony neat & clean = z
As per the question,equations become as