A carpet of size 3 m × 7 m has a border of red colour. The width of border is 25 cm. The inner part of carpet has blue colour. The area of blue colour is:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 16.25 m2
The red border runs along both ends of each side, so the blue inner part is shorter than the carpet by twice the border width in length and in breadth.
Border width \(=25\) cm \(=0.25\) m, so each side loses \(2\times0.25=0.5\) m
Inner length \(=7-0.5=6.5\) m
Inner breadth \(=3-0.5=2.5\) m
Blue area \(=6.5\times2.5=16.25\,\mathrm{m^2}\)
Tip: Subtract the border width twice from each side. Taking it off only once gives \(6.75\times2.75=18.5625\), which is Option (3).