Stiv wrote:
A certain one-day seminar consisted of a morning session and an afternoon session. If each of the 128 attending the seminar attended at least one of the two sessions, how many of the people attended the morning session only?
(1) 3/4 of the people attended both sessions.
(2) 7/8 of the people attended the afternoon session.
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. Since "each of the 128 people attending the seminar attended at least one of the two sessions", then there are no one who attended neither of sessions. So, we have that:
{Total} = {Morning} + {Afternoon} - {Both}.
(1) 3/4 of the people attended both sessions. 3/4 of 128 is 96. So we know that 96 people attended both seminars. If you draw Venn diagram you'll see that 96 is the intersection of the people who attended morning session and the evening session. This only tells that minimum # of people for the morning session is 96.
Morning only could be from 0 to 32. Not sufficient.
(2) 7/8 of the people attended the afternoon session. 7/8 of 128 is 112. So, 112 people attended the afternoon session. Since
each of the 128 people attending the seminar attended at least one of the two sessions hence rest of the people 16, must have been attending the morning session and not attending the evening, which IS only morning session attendant #. Sufficient. (
{Total} = {Morning} + {Afternoon} - {Both} -->
128 = {Morning} + 112 - {Both} -->
{Morning} - {Both} = 16).
Answer: B.
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34% (02:07) correct
