21. A certain type of mixture is prepared by mixing brand A at Rs.9 a kg. with brand B at Rs.4 a kg. If the mixture is worth Rs.7 a kg., how many kgs. of brand A are needed to make 40kgs. Of the mixture?
Ans. Brand A needed is 24kgs
22. A wizard named Nepo says “I am only three times my son’s age. My father is 40 years more than twice my age. Together the three of us are a mere 1240 years old.” How old is Nepo?
Ans. 360 years old
23. One dog tells the other that there are two dogs in front of me. The other one also shouts that he too had two behind him. How many are they?
24. A man ate 100 bananas in five days, each day eating 6 more than the previous day. How many bananas did he eat on the first day?
25. If it takes five minutes to boil one egg, how long will it take to boil four eggs?
Ans. Five minutes.
26. The minute hand of a clock overtakes the hour hand at intervals of 64 minutes of correct time. How much a day does the clock gain or lose?
Ans. 32 8/11 minutes.
27. Solve for x and y: 1/x – 1/y = 1/3, 1/x2 + 1/y2 = 5/9.
Ans. x = 3/2 or -3 and y = 3 or -3/2.
28. Daal is now being sold at Rs. 20 a kg. During last month its rate was Rs. 16 per kg. By how much percent should a family reduce its consumption so as to keep the expenditure fixed?
Ans. 20 %.
29. Find the least value of 3x + 4y if x2y3 = 6.
30. Can you find out what day of the week was January 12, 1979?