Question

A car went 60 km in 5/6 of an hour while a second car went 54 km in 2/3h. Which car was faster? How many times faster?

Answer 1

Answer:

The car that went 54 km in 2/3h was faster, 5/4 times faster than the other car

Explanation:

Average speed of a car is the ratio between the displacement $\Delta x$ and the time (t) it takes to do that displacement:

$V_{avg}=\frac{\Delta x}{t}$

So, for the first car:

$V_{avg1}=\frac{60km}{\frac{5h}{6}} =72\frac{km}{h}$ (1)

for the second car we have:

$V_{avg2}=\frac{60km}{\frac{2h}{3}} =90\frac{km}{h}$ (2)

So, the second cart is faster than the first one. To find how many times divide speed 2 by speed 1:

$\frac{90}{72}=\frac{5}{4}$