The everage mass of three men is:
(a + b) / 3 = 77, where a is mass of two first men combined and b is a mass of third man.
The everage mass of two men is:
a / 2 = 72.5, therefore
a = 145, and
(145 + b) / 3 = 77
145 + b = 231
b = 231 - 145 = 86
Answer: Mass of the third man is 86 kg.
They are already available in some areas of the United States, and Sony is currently trying to distribute them to retailers.
The balloon has a greater affinity for electrons so it obtains a negative charge after being rubbed against the sweater. The balloon, containing a highly negative charge, sticks to the wall because it is attracted to the positive charges in the wall (opposites attract). After a while, the balloon's extra electrons move to the wall and both objects become neutrally charged. Lacking any significant attraction, the balloon will fall off the wall.
Ski jumpers train in a similar fashion to other top athletes. It takes years of training to reach professional or Olympic status.