If you and your mother ride a bike from home to grandma's house at a speed of 4 meters per second, then the distance difference between you and your father is.

25*60*4=6000 。 The total distance is 4*40*60=9600. Assuming that the meeting time without distance restriction is t, then

For 9T=4T+6000, T= 1200s. Total encounter distance s = 9t =10800 >; Actual total distance =9600. So we can't catch up.

9600 = V * (40-25) * 60V =160/15 = 32/3 = about 10.67.