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19 Apr 2022, 07:11
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A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
55%
(hard)
Question Stats:
57% (01:31) correct
43%
(01:28)
wrong
based on 228
sessions
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There are 300 people in a conference hall. Each person is either an engineer or a professor or both or only a journalist. What is the probability that a person randomly picked from the hall is a journalist?
(1) There are 200 people who are an engineer or a professor.
(2) There are 200 people who are exclusively an engineer or a professor.
Are You Up For the Challenge: 700 Level Questions
(1) There are 200 people who are an engineer or a professor.
(2) There are 200 people who are exclusively an engineer or a professor.
Are You Up For the Challenge: 700 Level Questions
20 Apr 2022, 03:45
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1) Tells us that there are 200 people in the conference hall who are either an engineer, professor or both, or that \((E or P) = 200\). Plugging that into \(300 = (E or P) + J\) will give:
\(300 = 200 + J\)
\(J = 100\), which means that the probability that a person randomly picked from the hall is a journalist is: \(\frac{1}{3}\)
SUFFICIENT
2) Tells us that there are 200 people who are either engineers or professors, but nothing about how many are both.
With this we get the equation \(300 = E + P - (E or P) + J\)
\(300 = 200 - (E or P) + J\)
\(100 = -(E or P) + J\)
INSUFFICIENT
Answer A
\(300 = 200 + J\)
\(J = 100\), which means that the probability that a person randomly picked from the hall is a journalist is: \(\frac{1}{3}\)
SUFFICIENT
2) Tells us that there are 200 people who are either engineers or professors, but nothing about how many are both.
With this we get the equation \(300 = E + P - (E or P) + J\)
\(300 = 200 - (E or P) + J\)
\(100 = -(E or P) + J\)
INSUFFICIENT
Answer A
16 Jun 2022, 19:07
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The easiest way is to draw a Venn diagram in such a question.
- As the question suggests, only the ticked regions are allowed and thus we can say, A + B + C + D = 300 ... (1)
And the answer we are looking for is \(\frac{D}{(A + B + C + D)}\)
So we are looking for D to get the answer.
Statement 1
There are 200 people who are an engineer or a professor.
- This means A + B + C = 200
Thus, subtracting this from (1) we get D = 100.
And the answer = \(\frac{D}{(A + B + C + D)}\) = \(\frac{100}{(300)}\) = \(\frac{1}{3}\) (Calculation not needed)
This is sufficient and we can eliminate options B, C, and E.
Statement 2
There are 200 people who are exclusively an engineer or a professor
- This means A + C = 200.
But to know D, we need to know B and that is not given
This statement is not sufficient.
The answer is A.
