Question

You normally drive on the freeway between San Diego and Los Angeles at an average speed of 105 km/h (65 mi/h), and the trip takes 1 h and 50 min. On a Friday afternoon, however, heavy traffic slows you down and you drive the same distance at an average speed of only 70 km/h (43 mi/h). How much longer does the trip take?

Answer 1

Answer: 2 hr 45 min

Explanation:

Given

The average speed between San Diego and Los Angeles is $105\ kmph$

time taken for this trip is  $1\ hr\ 50\ min\ or\ \frac{11}{6}\ hr$

Distance between San Diego and Los Angeles is

$\Rightarrow d=105\times \dfrac{11}{6}\\\\\Rightarrow d=192.5\ km$

For Friday afternoon, the average speed is  $70\ km/h$

time taken to complete the trip is

$\Rightarrow t=\dfrac{192.5}{70}\\\\\Rightarrow t=2.75\ hr\ or\ 2\ hr\ 45\ min$