leanne's answer to Dominic John's Primary 5 Maths Area & Volume Singapore question.

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leanne
Leanne's answer
187 answers (A Helpful Person)
1st
Given length : breadth = 2:1
Let breadth of each rectangle = x cm
Hence length = 2x cm

We can calculate perimeter( 286cm) by using observation of how many times lengths and breadths appear and additional of those overlapping ones = 6 lengths + 6 breadths + 4 overlapping ones of x cm
= 6 (2x) + 6x + 4(x) = 12 + 10 = 22x

286cm = 22x
Therefore x = 286 / 22 = 13cm

Hence breadth (x)= 13cm
Length (2x) = 13 (2 )= 26cm


Or: calculate each rectangle sides individually
E.g rectangle 1= x +2x+2x = 5x
Rectangle 2= x + x + x + x = 4x
Etc.
until rectangle 5

Area of 1 rectangle= Length multiply by breadth
= 26 (13) = 338 cm 2
Dominic John
Dominic John
4 years ago
Im primary 5, bit in jc