15. The average of five consecutive odd numbers is 61. What is the difference between the highest and lowest numbers?
D.Cannot be determined
16. The sum of three consecutive odd numbers is 38 more than the average of these numbers. What is the first of these numbers?
17. The average age of the boys in a class is 16 years and that of the girls is 15 years. The average age for the whole class is :
D.Cannot be computed with the given information
18. A library has an average of 510 visitors on Sundays and 240 on other days. The average number of visitors per day in a month of 30 days beginning with a Sunday is :
19. If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55 and 60, then the average marks of all the students is :
D.None of these
20. The average weight of 16 boys in a class is 50.25 kgs and that of the remaining 8 boys is 45.15 kgs. Find the average weight of all the boys in the class
21. A car owner buys petrol at Rs 7.50, Rs. 8 and Rs. 8.50 per litre for three successive years. What approximately is the average cost per litre of petrol if he spends Rs. 4000 each year ?
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