NAP Yr 9 Example Test: Numeracy Q28 - 47.5 cm?

[vincentlu]

http://www.nap.edu.au/verve/_resources/Example_Test_Numeracy_Y9_calc.pdf

Question 28 says 46 centimeters in the answers but i got 47.5 centimeters

 

[MarkFL]

I get 46 cm². Can you post your work so we can see what you did wrong?

 

[phymat]

View attachment 4369

I get 46 too, but in meters and not in centimeters! (which makes a huge difference) (Sweating)

Areas of triangular faces are already given. We just need to find separate areas of all rectangular faces and add all triangular-face-areas to rectangular-face-areas in order to get the total area.

$$3+3+(5 \times 2.5)+(5 \times 2.5)+(5 \times 3) = 46 \text{m}^{2}$$

Also, I tried many experiments to find a situation where someone gets confused and gets the answer as $$47.5$$ by mistake, but found no such situation!