The average time for a reasonable swimmer aged 10 years for 50 meters breastroke is around 55 seconds. Breastroke is a very technical stroke and therefore harder to master properly and efficiently.
An average 100 meter swim time is 1 minute and 33 seconds.
If you average 60 miles per hour for the entire distance your driving time would be about 28 hours and 40 minutes.
Around about a minute
The answer is 15.2 seconds.
Average speed = Distance divided by time taken and the unit is meters per second (written m/s), so remember to convert distance to meters and time to seconds if it not already given to you as these.
To get average speed, divide distance travelled by the time. The answer will be in meters/second. If you want to have your result in km/hour, multiply the number of meters/second by 3.6.
Since length is measured in meters, and time in seconds, it follows that speed is measured in meters/second.