16.

The average of six numbers is x and the average of three of these is y. If the average of the remaining three is z, then :

A) x = y + z

B) 2x = y + z

C) x = 2y + 2z

D) None of these

17.

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 ?

A) Rs. 7.98

B) Rs. 8

C) Rs. 8.50

D) Rs. 9

18.

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.

A) 47.55 kgs

B) 48kgs

C) 48.55 kgs

D) 49.25 kgs

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 :

A) 53.33

B) 54.68

C) 55

D) None of these

20.

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 :

A) 250

B) 276

C) 280

D) 285

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