A survey has been conducted on methods of commuter travel. Each respondent was asked to check Bus, Train or Automobile as a major method of travelling to work. More than one answer was permitted. The results reported were as follows : Bus 30 people; Train 35 people; Automobile 100 people; Bus and Train 15 people; Bus and Automobile 15 people, Train and Automobile 20 people; and all the three methods 5 people. How many people completed the survey form?
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Correct answer: A. 120
Explanation
|B ∪ T ∪ A| = 30 + 35 + 100 − 15 − 15 − 20 + 5 = 120.
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