Calculate Delivery Van Speed Using Distance and Time

This problem asks us to find the constant speed of a delivery van given the distance it traveled and the time it took. We need to express the speed in kilometers per hour (km/hr) and round it to the nearest whole number.

Understanding the Speed Formula

The relationship between speed, distance, and time is fundamental in physics. The formula used is:

$ \text{Speed} = \frac{\text{Distance}}{\text{Time}} $

Where:

• Speed is measured in units like km/hr.
• Distance is the total length covered, measured in kilometers (km).
• Time is the duration of the travel, measured in hours (hr).

Applying the Formula to the Problem

We are given the following information:

• Distance = 156 km
• Time = 3.5 hours

Now, we substitute these values into the speed formula:

$ \text{Speed} = \frac{156 \text{ km}}{3.5 \text{ hours}} $

Performing the Calculation

Let's calculate the value:

$ \text{Speed} = 156 \div 3.5 \approx 44.5714 \text{ km/hr} $

Rounding the Speed

The question requires the speed to be rounded off to the nearest whole number. We look at the decimal part of our calculated speed (44.5714...). Since the first decimal digit (5) is 5 or greater, we round up the whole number part.

Rounding 44.5714... to the nearest whole number gives us 45.

Final Speed Result

Therefore, the constant speed of the delivery van is approximately 45 km/hr.