Balancing % down payment vs interest-rate/closing-cost for home

[Nivin Lawrence]

I am looking for some advice on how to choose between a 10% downpayment with higher interest rate and closing cost vs a 20% down payment with lower interest rate and closing cost. Both options don't need a mortgage interest and i am looking at a 7/1 ARM. If i go with the 10% down, I need to make approx 7% returns yearly (for the 7 years considered) on the saved down-payment to cover for the higher interest/cost associated with this option to match the 20% down option. Are there investment options with this kind of returns or am i better off putting the 20% down?