Question

What is the average speed of the car if it covers 200 km in 5 hours (in km/h)?

• A. 50
• B. 60
• C. 35
• D. 40

Hint:

Average speed is always Total Distance $\div$ Total Time --- never the arithmetic mean of individual speeds unless the time durations are equal. If a car covers the first half in time $t_1$ and second half in time $t_2$, the average speed is $\dfrac{d}{t_1+t_2}$, not $\dfrac{v_1+v_2}{2}$. Always go back to the basic formula.

Answer 1

The Correct Option is D

Step 1: Recall average speed.
Average speed is the total distance travelled divided by the total time taken. It works whether the motion was steady or not.

Step 2: Write the formula.
\[ \text{Average speed} = \frac{\text{total distance}}{\text{total time}} \]

Step 3: List the given values.
The distance is $200$ km and the time is $5$ hours.

Step 4: Substitute the values.
\[ \text{Average speed} = \frac{200}{5} \]

Step 5: Do the division.
$200$ divided by $5$ gives $40$.

Step 6: State the result with units.
The car covers $40$ km in each hour on average. So the average speed is \[ \boxed{40\ \text{km/h}} \]