The total trade of 5 years is 3800, 3600, 2800, 3900 and 5000 crore dollars respectively. What is the difference (in crore dollars) in the average exports and average imports respectively?

Difference between export and import in each year respectively (in crore dollars) :

Year 1 : $$\frac{(10-9)}{(10+9)}\times3800$$ = 200

Year 2 : $$\frac{(11-7)}{(11+7)}\times3600$$ = 800

Year 3 : $$\frac{(4-3)}{(4+3)}\times2800$$ = 400

Year 4 : $$\frac{(5-8)}{(5+8)}\times3900$$ = -900

Year 5 : $$\frac{(12-13)}{(12+13)}\times5000$$ = -200

=> Required average = $$\frac{(200+800+400-900-200)}{5}$$

= $$\frac{300}{5}=60$$

=> Ans - (A)