Question

The sides of a rectangle are 250 mm and 1.5 m. The perimeter in cm is?
A) 450
B) 350
C) 250
D) 550

Answer 1

Hint: The perimeter of any shape/polygon is the sum of lengths of all sides of the shape/polygon. So, here for a rectangle, the perimeter would be the sum of (length and breadth) times two because the opposite sides of a rectangle are equal.
Formula used-
Perimeter of a triangle is given by
$P = 2\left( {l + b} \right)$ where l and b are the length and breadth of a rectangle.

Complete step-by-step answer:
First of all, we should make a diagram to visualise the problem given in the question.
Here, we can see that the sides of the rectangle are given as 1.5m and 250\;mm.
So, before proceeding we have to convert the lengths in one unit so that we can apply the rules of arithmetic.
Length = $l = 1.5\;m = 1.5 \times 100\;cm = 150\;cm$
Breadth = $b = 250\;mm = 250 \times \dfrac{1}{{10}}\;cm = 25\;cm$
Now, according to this we can draw the diagram as

Now, to find perimeter we have to add up the lengths of the sides i.e. length and breadth of rectangle.
Perimeter= length + breadth + length + breadth
$
  P = l + b + l + b \\
   \Rightarrow P = 2l + 2b \\
   \Rightarrow P = 2\left( {l + b} \right) \;
 $
Substituting, the values in the above equation, we get
$
   \Rightarrow P = 2\left( {150\;cm + 25\;cm} \right) \\
   \Rightarrow P = 2\left( {175cm} \right) \\
   \Rightarrow P = 350\;cm \;
 $
Therefore, the perimeter of the given rectangle is 350 cm and the correct option is B)
So, the correct answer is “Option B”.

Note: In this question, it is important to note that we have only converted the lengths to cm because the options are given in that way. Although it is not necessary to convert lengths in centimeters, it is very much important to convert the units to the same. For example, if the question didn’t command the final answer to be in centimeters, then we could also have converted the sides in millimeter units.
$1.5m = 1.5 \times 1000\; mm = 1500\;mm$ and then calculate the perimeter accordingly.