Answer:
$4.50
Step-by-step explanation:
In order to make a profit from the futures contracts, it would be appropriate to take a long position in the June futures contract(buy) and take a short position in the December futures contract.
The investor would borrow $60 today which would necessitate paying back $60 plus a half-year in interest payment.
loan repayment=$60*(1+5%/2)=$ 61.50
In December, sell crude oil at $66 and repay the loan principal and interest
profit=$66-$61.50=$4.50