Question 12349
your problem is wrong and the statement should read to make a mixture costing $1.60 per KG and not to be sold off at 1.60 per kg

Now this is an alligation question the ratio of cheaper qtty  to dearer qtty can be solved by the formula

c:d = (d-m)/(m-c)

c - cheaper qtty(1.5 in this case), d: dearer qtty(1.9 in this case), m: mean qtty(1.6 in this case)

So c:d = (1.9-1.6)/(1.6-1.5)

on solving the ratio is 3:1 so if dearer qtty is 1 cheaper qtty is 3
             thus if dearer qtty is 200 kg, the cheaper qtty should be 600 Kg.