1. C = 2(pi)(r)        = 2(pi)(0.7)        = 7/5 pi
So, the circumference of a circle is 7/5 pi.
2. time = distance/speed            = 2.4/15            = 4/25
So, the dart is in the air for 0.16(4/25) sec.
3. I am not sure if this answer is right but I guess the probability of getting no tails is 2:1 (heads:tails)
HOPE THIS HELPS!!!!