Standard Mathematics Primary 6 Ratio

A scale-model architect at a Tampines HDB showroom uses a model where the ratio of model length to actual length is $5 : 8$. The model length of the living room is $35$ cm. What is the actual length, in centimetres?

A 56
B 38
C 70
D 44
Show Worked Solution

Worked Solution

Step 1: Set up the equivalent ratio with the unknown actual length x: $5 : 8 = 35 : x$.\n Step 2: Find the multiplier from the first term to its equivalent: $35 \div 5 = 7$.\n Step 3: Equivalent ratios are obtained by multiplying BOTH terms by the same number. Multiply the second term by 7: $x = 8 \times 7 = 56$.\n Step 4: The actual length is 56 cm.\nCheck: $35 : 56 = 5 : 8$ (divide both by 7). ✓ Answer: 56

Correct answer: 56

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