The exact theoretical futures price using continuous compounding is $F = S \times e^{(r_{US} - r_{EU}) \times T} = 1.098 \times e^{(0.015 - 0.0125) \times 1.5} \approx 1.1021$ USD per Euro. The quoted futures price is $1.100$USD per Euro. Since the quoted futures price is lower than the theoretical futures price, there is an arbitrage opportunity. The arbitrage gain per Euro at maturity is the difference: `$1.1021 - 1.100 = 0.0021$ USD. For an investment of $1000`$ Euros, the arbitrage gain is $1000 \times 0.0021 = `$2.1`$.