In a certain party, every person drinks either tea or coffee. If 60%

Question

In a certain party, every person drinks either tea or coffee. If 60% drink tea and 70% drink coffee, what is the probability that a person drinking tea also drinks coffee?

A. 1/2
B. 1/6
C. 1
D. 3/10
E. 21/50

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Ashokvardhan · Accepted Answer

The question is about the probability of people drinking tea and also coffee
drinking tea = 60 
both = 30
probability = 30/60 =1/2
hence A
At first even I marked D but reading the question thrice helped me to get the logic

bacca2323 · Answer

Total = 100
C = Coffee = 70
T = Tea = 60
Neither Tea nor Coffee = 0 (the text says so) 
100 = 60 + 70 + 0 - x
x = 30 (people who drink both Tea and Coffee) 
So the chance is 30/100 that is 3/10. 
Hence Number D imo.

Kinshook · Answer

In a certain party, every person drinks either tea or coffee. If 60% drink tea and 70% drink coffee, what is the probability that a person drinking tea also drinks coffee?

Drinks Tea 
 ~Drinks Tea 
 Total 
 
  Drinks Coffee 
 30% 
 40% 
 70% 
 
  ~Drinks Coffee 
 30% 
 0% 
 30% 
 
  Total 
 60% 
 40% 
 100%

The probability that a person drinking tea also drinks coffee = 30%/60% = 1/2

IMO A

onlymalapink · Answer

i d9nr understand the probabilty done in the end it doesnt make sense ro me30/60 why

hr1212 · Answer

Conditional probability P(A/B) =  \frac{P(A ∩ B)}{P(B)}  ie. probability of event A such that event B occurs

Here, P(Coffee/Tea) =  \frac{P({Coffee ∩ Tea})}{P(Tea)} , where,

P(Coffee ∩ Tea) = 30/100 = 3/10 
 P(Tea) = 60/100 = 6/10

which means, P(Coffee/Tea) =  \frac{3/10}{6/10}  =  \frac{1}{2}

Answer : A

shivani1351 · Answer

This question isn't difficult, but due to one of the language traps in the question, you might guess the answer as D, instead of A.

The trap lies in the ending of the question, specifically this part - probability that a  person drinking tea also drinks coffee

Let the total number of persons be 100X
Tea - 60X
Coffee - 70X

100X = 60X + 70X - (Persons drinking both tea and coffee)

Therefore, the number of persons drinking both tea and coffee = 30X

We are required to find out the probability that a  person drinking tea also drinks coffee , which translates to:

Number of persons drinking both tea and coffee / Number of persons drinking tea

30X/60X = 1/2

Note:  Since the question specifically asks for the number of persons drinking tea who also drink coffee, we equate the denominator to the total number of persons drinking tea.

In a certain party, every person drinks either tea or coffee. If 60%

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	Drinks Tea	~Drinks Tea	Total
Drinks Coffee	30%	40%	70%
~Drinks Coffee	30%	0%	30%
Total	60%	40%	100%

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In a certain party, every person drinks either tea or coffee. If 60%

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