I answered $2 for Q18, but i got an interesting response from a teacher, who said such:
The answer is $4.
Why?
It is all to do with the law of supply (Y11 Econ). Before the subsidy, At $10 there were all suppliers only willing and able to supply 12 towels to the market.
With the subsidy and a sale price of $10 all suppliers are now willing and able to supply 20 towels to the market.
I got a bit tricky after that - I looked at the total revenue for producers. That is price x Quanity for all suppliers.
Before subsidy it was 10x12 = $120
After subsidy it was 10x 20 =$200
So the difference in total producer revenue at $10 with the subsidy is $80. (the subsidy gives an extra $80 in revenue to suppliers)
Now to work out the $ per towel the subsidy - you have to divide it by the number of towels made , 20 made.
So $80/20 = $4
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I still take the opinion that the answer is $2 due to the vertical difference in supply's, but that would be the argument for $4