1. A person invested Rs 4400 in two parts one at 6% and the other at 10% rate of interest. If his over all gain is 9%, find the money invested at 6% interest.
2. The average age of P and Q is 20 years. If R were to replace P, the average would be 19 and if R were to replace Q, the average would be 21. What are the age of P, Q and R?
3. 3 years ago the average age of a family of 5 members was 17 years. With the birth of a new baby, the average age of six members remains the same even today. Find the age of the new baby.
4. The average of a batsman for 40 innings is 50 runs. His highest score exceeds his lowest score by 172 runs. If these two innings are excluded, his average drops by 2 runs. Find his highest score.
5. A family consists of grandparents, parents and three grandchildren. The average age of the grandparents is 67 years, that of the parents is 35 years and that of the grandchildren is 6 years. What is the average age of the family?
6. A man traveled one-third of journey with 10 m/sec; Two-third of remaining journey with 20 m/sec; rest of the journey with 30 m/sec. What is his average speed for whole journey in m/sec?
7. Six litres of a 20% solution of alcohol in water are mixed with 4 litres of a 60% solution of alcohol in water. Find the percentage of alcohol in the mixture.
8. A company blends two varieties of tea from two different tea gardens, one variety costing Rs 20 per kg and other Rs 25 per kg, in the ratio 5 : 4. He sells the blended tea at Rs 23 per kg. Find his profit percent.
9. The amount of water (in ml) that should be added to reduce 9 ml lotion, containing 50% alcohol, to a lotion containing 30% alcohol, is:
10. Three math classes X, Y and Z take an algebra test. The average score in class X is 83. The average score in class Y is 76. The average score in class Z is 85. The average score of all students in classes X and Y together is 79. The average score of all students in classes Y and Z together is 81. What is the average score for all the three classes?