Question
Mathematics Question on Probability
In a certain laboratory, chemicals are identified by a colourcoding system. There are 20 different chemicals. Each one is coded with either a single colour or a unique twocolour pair. If the order of colours in the pair doesn't matter, then what is the minimum number of differentcolours needed to code all the 20 chemicals with either a single colour or a unique pair of colours?
A
5
B
7
C
6
D
20
Answer
6
Explanation
Solution
The correct option is (C) : 6