The probability that they do not use the swimming pool will be 0.2.
From the information given, there are 135 people in a sport centre and 31 people use the gym and the track while 4 people use all three facilities.
Based on the information given, the people who use the gym and the track only will be:
= 31 - 4
= 27
The probability that they do not use the swimming pool will be:
= 27/135
= 0.2
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