**11. A number is decreased by 20% and then increased by 40%.Find the percentage change in the number. **

**12. The price of 4 apples and 6 mangoes is Rs.62 and the price of 6 apples and 4 mangoes is Rs.58. Find the price of 3 apples and 5 mangoes. **

**13. A die and a coin are tossed simultaneously. The probability that the die showing a prime number and the coin showing a head is **

**14. In what ratio should a class with average marks 34 be mixed with a class with average 22, so that the average of the mixed class is 31. **

**15. Find the value of `[(0.8)^3 – (0.2)^3]/[(0.8)^2 + 0.16 + (0.2)^2]` **

**16. Find the number of divisors of 36 excluding 1 and 36. **

**17. Find the greatest **

**18. In how many ways can a person put 4 letters in 4 envelopes such that exactly three letters are in their respective envelopes? **

**19. How many numbers can be formed between 200 and 1200, using the digits 0, 1, 2 and 3, such that there is no repetition? **

**20. If 6x^2 + 6y^2 = 13xy, find x:y. **