Answer:
- <u><em>Mr. Plum</em></u><em> killed Mrs. White.</em>
Explanation:
<u>1) Wavelengths for the different light colors (visible light) and related character:</u>
Color Wavelength related character
Violet 380–450 nm ← Professr Plum
Blue 450–485 nm ← Mrs. Peacock
Cyan 485–500 nm
Green 500–565 nm ← Mr. Green
Yellow 565–590 nm ← Colonel Mustard
Orange 590–625 nm
Red 625–740 nm ← Miss Scarlet
<u>2) At the time of the murder, the spectrometers recorded:</u>
a) In the <em>dining room</em>: <em>520 nm</em>.
520 nm is in the range 500 - 565 nm, which is the range for green color, so <em>Mr. Green</em> was in the dining room and is no more a suspect.
b)<em> In the lounge and study: lower frequencie</em>s.
Since frequency and wavelength are inversely related, the wavelengths in the longe and study have to be of <em>yellow and red</em> colors, which are the only two with longer wavelengths from the option given.
Then, <em>Mustard and Scarlet</em> are not criminal.
c)<em> In the library: the second shortest wavelength of the five recorded. </em>
<em />
The second shortest wavelength, as per the table, is that of <em>blue </em>color. So, <em>Mrs. Peacock</em> is not the killer.
The only left option is violet, so Mr. Plum is the only who could be at the conservatory and he is the killer.
, we can simplify the fraction to 