Question

A pole is painted red and white. The red portion is $1.8m$ and the white portion is three times as long as the red portion. How long is the pole?
A). $5.4m$
B). $7.2m$
C). $3.6m$
D). None of these

Answer 1

Hint: Type of questions are basically based on linear equations in one variable. For the type of problems according to concept we have to assume the unknown value to some variable, then relate it with the given value according to the condition given in the question, through where we will get the relation in unknown and known value and by solving we will get the unknown value.

Complete step-by-step solution:
As in our case we have a red and white portion, as the red portion length is $1.8m$and white portion is three times that of red. So we can say that if we multiply three with the length of the red portion we will get the value equal to that of white portion, from here we will get the relation between unknown and known value and by further solving we will get the white portion length.
So moving ahead with the question we have;
Length of red portion given $=1.8m$
Let the length of white portion be $=x$(which is variable)
So according to the question we have white portion three times that of red, so in order to equate both if we multiply the red portion with three then we will have the red portion equal to that of red. So we can write it as; white portion$=$$3\times $red portion
\[\begin{align}
  & white\text{ }portion=3\times red\text{ }portion \\
 & x=3\times 1.8 \\
 &\Rightarrow x=5.4 \\
\end{align}\]
Hence white portion is $5.4m$.
Now we find the length of pole which will be = Red portion+white painted portion=$1.8+5.4=7.2$
Hence the pole is 7.2m long, so the option B is the correct option.

Note: For the type of question we just had to find any relation between the values, on further solving we will get the answer. Moreover, as we had multiplied by three in the red portion to equate, we can also divide white portion by three to equate it to the red portion; that will also be right.