Question

(a) Find the average speed of the bus. An express bus covered 560 km in 7 hours. (b) If the speed of the bus was 70 km/h instead, how long did the bus take to cover the distance?​

Answer 1

Step-by-step explanation:

The formula we want to use is s=v⋅t . Where

• s is distance

• v is velocity

• t is time

This will show up so many times for you that I really recommend you to memorize it. Write your known parameters as variables in s,v and t .

• s1 =120 km

• v1= unknown

• t1 = 3h

• s2 = 150 km

•v2 = v1 (same speed for both trips )

• t2 = wanted

For both trips we have

$\frac{s}{t} = v$

Since v is the same for both trips then

$\frac{s1}{t1} = \frac{s2}{t2}$

Solve for t2

$t2 = t1 \times \frac{s2}{s1}$

Doesn’t this seem very intuitive? If you double the distance the time needed doubles as well? Connect it with a trip you’ve recently made. If you needed to go 20 % further the time should increase by 20 % as well right? Also note that we didn’t need to find the velocity at all! Neat right?

•

$t2 = 3h \times \frac{150}{120} = 3.75$

✍ Hope it's helpful to you ✍