Unit 4
4 marks · EasyA student wants to convert 0.72 to a fraction and then use this value in a substitution problem.
Express 0.72 as a fraction in its simplest form.
In the equation , substitute and find the value of .
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) 18/25 · must show Correctly simplified fraction
(b) 18
Common mistakes: Using 72/100 instead of simplest form; Wrong calculation in substitution
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Marking points
B1 (a) · 2 marks · Writes 0.72 as 18/25 in simplest form
M1 (b) · 1 mark · Substitutes d = 0.72 into n = 25 d
A1 (b) · 1 mark · Finds correct value n = 18
Worked solution
a) 0.72 = 72/100. Simplify by dividing numerator and denominator by 4: 72 ÷ 4 = 18, 100 ÷ 4 = 25. So 0.72 = 18/25.
b) n = 25 × 0.72 = 18.