battery life

Buy a battery checker

You are (I am sure) aware that nobody can give you a proper answer given so little data. The battery is rated in mAh (the number of miliamps it can deliver for an hour. To estimate how long the battery can be used, you need to know how much current you will be drawing. The receiver has a fixed drain, but the servo current will vary depending on use. The more you move a control, the more its servo will draw.
Your best bet is to buy an expanded scale voltmeter to monitor the voltage remaining. Ones for hobby use are calibrated red or green for go or no go. I have a good spare I'll sell for $5.00 plus postage.
Jim - AMA 501383
jeffm wrote:

How long is a piece of string?
There are so many variables, that no one can answer your question. You need to either purchase a meter to measure the voltage or put a "volt minder" in the aircraft.