Multiple choice

A rectangle plot of land measures $45$ m $\times$ $30$ m. A boundary wall of height $2.4$ m is built all round the plot at a distance of $1$ m from the plot. Find the area of the inner surface of the boundary wall.

  1. $226.2m^{2}$
  2. $457.2m^{2}$
  3. $379.2m^{2}$
  4. $291.2m^{2}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The wall is 1m from the plot, so the dimensions of the wall perimeter are (45+2) and (30+2) = 47m and 32m. Perimeter = 2 * (47 + 32) = 158m. Area of inner surface = Perimeter * height = 158 * 2.4 = 379.2.

AI explanation

The inner surface area of the boundary wall is found by calculating the lateral surface area of the inner rectangular boundary, which is given by the formula perimeter times height. The perimeter of the inner boundary is 2 * ((45 + 2) + (30 + 2)), equaling 158 m. Multiplying this perimeter by the wall height of 2.4 m gives a total area of 379.2 square m.

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