Time (1) in minutes Frequency
0 5
10 < t < 20
12
20 17
40 < t < 60
6
Work out an estimate for the mean time the people spent mowing their lawns.

Identify all the cases where non-probability sampling is used when attempting to study the characteristics of a large city. studies on every subject in the population divide a population in groups and obtain a sample studies with a limited amount of time demonstrate existing traits in a population studies with the nth person selected