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Unitary Method - Questions

Question 1
29382

12 apples cost $5.40. How much will 15 apples cost?

\(\$ 6.75\)

\begin{aligned}
12 \text { apples } &=\$5.40 \\
1\text { apple } &=5.40 \div 12 \\
15\text { apples } &=15 \times 5.40 \div 12 \\
&=\$ 6.75
\end{aligned}

Question 2
29378

4 maths books cost $169.60. How much do 20 maths books cost?

$848

\begin{aligned}
4 \text { books } &=169.60 \\
1 \text { book } &=169.60 \div 4 \\
20 \text { books } &=20 \times 169.60 \div 4 \\
&=\$ 848
\end{aligned}

Question 3
29379

A cheetah can run 210 m in 7 seconds. How far can the cheetah run 1 minute?

\(1.8~\text{km}\)

\begin{aligned}
7 \text { seconds }=&210 \mathrm{~m} \\
1\text { second }=& 210 \div 7 \mathrm{~m} \\
=& 30 \mathrm{~m} \\
60 \text { second }=& 30 \times 60 \\
=& 1800 \mathrm{~m} \\
=& 1.8 \mathrm{~km}
\end{aligned}

Question 4
29380

A train travels 150 km at a constant speed for 1 hour and 40 minutes. How far will it travel at the same speed for 2 hours and 20 minutes?

\(210~\text{km}\)

\begin{aligned}
1 \text { hour } 40 \mathrm{~min} &=150 \mathrm{~km} \\
1 \frac{2}{3} \text { hour } &=150 \mathrm{~km} \\
1 \text { hour } &=150 \div 1 \frac{2}{3} \mathrm{~km} \\
&=90 \mathrm{~km} \\
2 \frac{1}{3} \text { hours } &=90 \times 2 \frac{1}{3} \\
&=210 \mathrm{~km}
\end{aligned}

Question 5
29381

A car uses 25 litres of petrol to travel 200 km. How far will it travel with 42 litres?

\(336~\text{km}\)

\begin{aligned}
25\text{ litres} &=200 \mathrm{~km} \\
1 \text { litre } &=200 \div 25 \\
42\text{ litres} &=42 \times 200 \div 25 \\
&=336 \mathrm{~km}
\end{aligned}