Question

To reach his office on time, Mr Chin usually drives to work at an average speed of 75 km/h. However, if Mr Chin increases his average driving speed by 5 km/h, he will reach his office 10 minutes earlier. If the distance Mr Chin needs to travel to reach his office is represented by x km, form an equation in x and solve for x.

Answer 1

Answer: x = 200 km

Explanation:

Distance(x) = Speed(s) x Time(t)

t is in hours

x=s*t

At 75km/h: 75*t = x

At 80km/h: 80*(t-(10/60)) = x [the -(10/60) is the 10 minutes saved, in hours]

We know the distance, x, is the same, so we can set these equal to each other:

75*t = 80*(t- (10/60))

75*t = 80*t - 13.3333

-5*t = -13.3333

t = 2 2/3 hours

Both situations should give the same distance with 2 2/3 and 2 2/3 - :

x = (75 km/hr) x ( 2 2/3 hr)= 200 km

x = (80 km/hr) x (2 2/3 - 1/6 hr) = 200 km