The value of g at sea level is 9.81 ms^-2.
The boy's mass is constant wherever he is in the universe but his weight will depend on the strength gravity where he is.
By proportion its value on the mountain peak is (360 /400) * 9.81
= 0.9 * 9.81 = 8.83 ms^-2 to nearest hundredth, (answer).
