Answer:
Negligible weights is a change so minor or insignificant to be deemed to have no effect on weight or balance.
In component form, the displacement vectors become
• 350 m [S] ==> (0, -350) m
• 400 m [E 20° N] ==> (400 cos(20°), 400 sin(20°)) m
(which I interpret to mean 20° north of east]
• 550 m [N 10° W] ==> (550 cos(100°), 550 sin(100°)) m
Then the student's total displacement is the sum of these:
(0 + 400 cos(20°) + 550 cos(100°), -350 + 400 sin(20°) + 550 sin(100°)) m
≈ (280.371, 328.452) m
which leaves the student a distance of about 431.8 m from their starting point in a direction of around arctan(328.452/280.371) ≈ 50° from the horizontal, i.e. approximately 431.8 m [E 50° N].
Radio waves are the waves with the lowest energy in the electromagnetic spectrum. X-rays and gamma rays are the highest. Sound is not part of the electromagnetic spectrum.
Explanation:
Let us assume that forces acting at point B are as follows.

= 0 ...... (1)
= 0
= 0 .......... (2)
Hence, formula for allowable normal stress of cable is as follows.

T = 
= 3925 kip
From equation (1),
= -3925
= -3925
= 12877.29 kip
From equation (2), -12877.29 (Cos 60) + W = 0
= 0
W = 6438.64 kip
Thus, we can conclude that greatest weight of the crate is 6438.64 kip.