Answer
1)Average cost of 10 fans equals 1440
2) 2
Steps
1)524/262
(2X262)/(2X131)
2 gets cancelled
(262)/(131)
(2X131)/(131)
131 gets cancelled
Equals 2
Steps
4 fans@ 1200 is 4800
6 fans @ 1600 is 9600
Hence 10 fans is (4800 plus
9600) equals 14400.
Hence average cost
14400/10
Equals 1440