**Question 9:**

Mr Wong is going to watch a movie at 2.30 p.m at a cinema that is 60 km away from his house. He leaves at 1.25 p.m and drives at an average speed of 70 km/h for half an hour. If he drives at an average speed of 75 km/h for the remaining journey, will he arrive before the movie starts?

**Give your reason with calculation.**

*Solution*:$\begin{array}{l}\text{Distancetravelledatthefirst}\frac{1}{2}\text{hour}\\ =70\times \frac{1}{2}\\ =35\text{km}\\ \\ \text{Remainingdistance}=60\text{km}-35\text{km}\\ \text{}=25\text{km}\\ \text{Timetakenfortheremainingjourney}\\ =\frac{25}{75}\\ =\frac{1}{3}\times 60\\ =20\text{minutes}\\ \\ \text{MrWongarrivesat}\\ =1.25\text{p}\text{.m}+30\text{minutes}+20\text{minutes}\\ =2.15\text{p}\text{.m}\\ \\ \text{Yes,hewillarrivebefore2}\text{.30p}\text{.m}\\ \end{array}$

**Question 10:**

Diagram below shows travel information of Jason and Mary from Town

*A*to Town

*B*. Jason drives a lorry while Mary drives a car.

(a) Jason started his journey from Town

*A*at 7.00 a.m.

State the time, Jason reached at Town

*B*.

(b) If both of them reached Town

*B*at the same time, state the time Mary started her journey from Town

*A*.

*Solution*:**(a)**

Total time taken from Town A to Town B

= 3 hours + 1 hour + 2 hours

= 6 hours

Time Jason reached Town B

= 0700 + 0600

= 1300 hours → 1.00 p.m.

**(b)**

$\begin{array}{l}\text{Speed}=\frac{\text{Distance}}{\text{Time}}\\ \text{TotaldistancefromTown}A\text{toTown}B\\ =\left(60\times 3\right)+\left(75\times 2\right)\\ =180+150\\ =330\text{km}\\ \\ \text{TimetakenbyMary}\\ =\frac{330}{100}\\ =3.3\text{hours}\\ =3\text{hours}18\text{minutes}\leftarrow \overline{)\begin{array}{l}0.3\times 60\\ =18\text{minutes}\end{array}}\\ \\ \text{ThetimeMarystartedherjourneyfromTown}A=9.42\text{a}\text{.m}\text{.}\end{array}$