Answer:
584.32m
Explanation:
Firstly, we need to find the x and y components of each vector.
x-component for vector L=303cos205°=-274.61
y-component for vector L=303sin205°=-128.05
x-component for vector M=555cos105°=-143.64
y-component for vector M=555sin105°=536.09
Since it's the vector sum, we add the x and y components of each vector.
Resultant vector x-component -274.61+(-143.64)=-418.25
Resultant vector y-component -128.05+536.09=408.04
Now, to find the magnitude, we use the formula 
sqrt(-418.25^2+408.04^2)=584.32m
Check my work for errors just in case.
Just so you know, total deafness is quite different than partial deafness.
Partial deafness can be any number of things. It can be an inability to make out the contents of high notes (notes with high frequencies and few harmonics).
Partial deafness can be the inability to hear low notes. I only know one person who suffers from that.
Your response to speech is quite different. Usually you have to have people look right at you. Lip reading is an art. Most deaf people between what they partially hear and lip reading can make out about 1/2 of what is said. Guessing usually takes care of the rest. Course you can get everything all muddled by guessing.
It does change your way of life. The TV is often turned up high enough that people living 4 houses down can list to the 6 o'clock news when you do.
Music is hard to make out. The overtones are lost.
Earphones have very tinny sound.
People are not as enjoyable as they once were.
(a) 
The relationship between frequency and wavelength of an electromagnetic wave is given by

where
is the speed of light
is the frequency
is the wavelength
In this problem, we are considering light with wavelength of

Substituting into the equation and re-arranging it, we can find the corresponding frequency:

(b) 
The period of a wave is equal to the reciprocal of the frequency:

And using
as we found in the previous part, we can find the period of this wave:

The answer is going to be B