Final answer:
The initial basis in March is +$0.14/lb, calculated by subtracting the cash price of $1.71/lb from the futures price of $1.85/lb. In September, the basis weakened, moving to -$0.01/lb as the cash price ($1.66/lb) fell below the futures price ($1.65/lb).
Step-by-step explanation:
The current basis can be calculated using the cash price and the futures price. The basis is the difference between the cash price and the futures price for the commodity. In the context provided, the current basis in March (when the prices are $1.71/lb cash and $1.85/lb futures) is calculated by subtracting the cash price from the futures price.
Current Basis = Futures Price - Cash Price
Current Basis = $1.85/lb - $1.71/lb
Current Basis = $0.14/lb
In September, the cash price is $1.66/lb and the futures price is $1.65/lb. The basis in September is then:
September Basis = Futures Price - Cash Price
September Basis = $1.65/lb - $1.66/lb
September Basis = -$0.01/lb
The basis has weakened because it has gone from +$0.14/lb to -$0.01/lb.