# Problem 2-62 - Distance and speed - Part 5 (a)

A truck travels at $80\; km/h$ for $30\; min$, then at $60\; km/h$ for $1.5 \;hr.$ Assuming 2 significant digits in the given numbers, calculate the truck's
(a) total distance traveled, and
(b) average speed.

Accumulated Solution

$\text{speed} = \frac{d}{\Delta t} \\ d = \text{(speed)} \Delta t \\ d_1 = 40\; km \\ d_2 = 90\; km$

Correct!

$d_2 = (60\; km/hr)(1.5\; hr) = 90\; km$

The total distance is (re-read the question):

(A)   $130\; km$

(B)   $1.3 \times 10^2\; km$

(C)   $1.30 \times 10^2\; km$