1. 3 pumps, working 8 hours a day, can empty a tank in 2 days. How many hours a day must 4 pumps work to empty the tank in 1 day?
2. If a quarter kg of carrots costs 60 paise, how many paise will 200 gms cost ?
3. The sum of 3rd and 15th elements of an arithmetic progression is equal to the sum of 6th, 11th and 13th elements of the same progression. Then which element of the series should necessarily be equal to zero ?
4. In a queue, Shankar is ninth from the rear end. Althaf's place is eighth from the front. Nitu is standing between the two. What could be the minimum numbers of boys standing in the queue ?