The problem is to find the departure time of a plane, given its arrival time (18:15), the distance it flew (216 miles), and its average speed (162 mph). We need to express the departure time using the 24-hour clock format.

1. Problem Description

The problem is to find the departure time of a plane, given its arrival time (18:15), the distance it flew (216 miles), and its average speed (162 mph). We need to express the departure time using the 24-hour clock format.

2. Solution Steps

First, we need to calculate the flight time.

The formula relating distance, speed, and time is:

$Distance = Speed \times Time$

Therefore,

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

Plugging in the given values:

$Time = \frac{216 \text{ miles}}{162 \text{ mph}}$

$Time = \frac{216}{162} \text{ hours} = \frac{4}{3} \text{ hours}$

Converting the time to hours and minutes:

$\frac{4}{3} \text{ hours} = 1 \frac{1}{3} \text{ hours} = 1 \text{ hour} + \frac{1}{3} \text{ hour}$

Since there are 60 minutes in an hour,

$\frac{1}{3} \text{ hour} = \frac{1}{3} \times 60 \text{ minutes} = 20 \text{ minutes}$

So, the flight time is 1 hour and 20 minutes.

The plane arrived at 18:

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5. To find the departure time, we need to subtract the flight time (1 hour 20 minutes) from the arrival time.

$18:15 - 1 \text{ hour} = 17:15$

$17:15 - 20 \text{ minutes} = 16:55$

3. Final Answer

The plane left Bristol airport at 16:

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5.