if you set up your chain properly yes. you should also get a 50 and 51 tooth chainrings. the way i was taught is to have 3 cogs and 3 chainrings to give you 9 close gear combinations. so you will get a gear chart that looks like this in gear inches (chainring/cog x 27):

___ 49 50 51
15 88.2 90 91.8
16 82.7 84.4 86
17 77.8 79.4 81

this way you can make small adjustments to your gear depending on the type of race or training, weather time of season etc.