Question

A certain one-day seminar consisted of a morning session and an afternoon session. If each of the 128 people attending the seminar attended at least one of the two sessions, how many of the people attended the morning session only?

Answer 1

Answer: 64 people attended to the morning session only.

Explanation:

They told us that each one of the 128 people attended at least one of the two sessions of the one-day seminar. We don't know for sure to which one of the sessions they attended, we only know that every person attended at least one. The probability of one person going to the morning session is the same as the probability that they will go to the afternoon session: 50%. To get the number of persons that attended the morning session only, we simply have to perform the product between the probability and the total number of potential attendees to the seminar. Let N be the total number of attendes, M the number of persons going to the morning session only and P the probability of those persons actually going to that session:

`M = N * P = 128 * 0.5 = 64`

So the total number of persons that attended the morning sessions only is 64.