A humming bird flaps its wing 5,000 times a minute when hovering in place. How many times will it flap its wings in 15 seconds?

To find the number of times the hummingbird will flap its wings in 15 seconds, we need to convert 15 seconds to minutes. There are 60 seconds in a minute, so 15 seconds is equal to 15/60 = 0.25 minutes.

Therefore, the hummingbird will flap its wings 5,000 * 0.25 = <<5000*0.25=1250>>1250 times in 15 seconds. Answer: \boxed{1250}.