ormaybesaladqh

2022-10-14

There was a question in my exam discrete maths that I just couldn't figure out. I know it's supposed to be solved using the inclusion-exclusion principle. anyone able to help me solve and understand this question.

For a survey, 200 people are asked about which forms of transport the had used in the last month it was found that

150 used trains,

80 had cycled and used trains, and

180 had used one or the other of these two forms of transport.

Question: How many people had cycled in the last month?

Question: How many had not used either form of transport.

For a survey, 200 people are asked about which forms of transport the had used in the last month it was found that

150 used trains,

80 had cycled and used trains, and

180 had used one or the other of these two forms of transport.

Question: How many people had cycled in the last month?

Question: How many had not used either form of transport.

lefeuilleton42

Beginner2022-10-15Added 12 answers

LET c and t denote cycle and train.

$$c\cup t=180$$

$$c\cap t+80$$

t=150

180=c+150−80

c=110

Those who did not use any of the two transportations are

200−180=20

$$c\cup t=180$$

$$c\cap t+80$$

t=150

180=c+150−80

c=110

Those who did not use any of the two transportations are

200−180=20

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EDIT

Here are two other questions from the exam, that the instructor said followed the same logic as the question above.

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