RRB Assistant Loco Pilot and Technician Model Paper 16 with key

Question : 44 of 75

Marks: +1, -0

There are in all, 10 balls; some of them are red and the others white. The average cost of all balls is Rs. 28, average cost of red balls Rs. 25 and that of white balls is Rs. 30, the number of white balls is: