Smokers/Drinkers

[sukrant26]

In a survey of 150 persons, how many were smokers and drinkers?
(I) 80% of the person surveyed were drinkers
(II) 40% of the smokers were drinkers also



I find such problems confusing.
Please explain

[xilef]

I
We have 80% or 120 who drank. We only know that 30 only smoked and X smoked and drank.

II

40% of those who smoked also drank, not useful at all.

I and II

We have 120 who drank, this group also includes the 40% of the smokers that drank and smoked, which means that 60% only smoked.

120+.6x=150
x=50 smokers of which 20 smoked and drank

Answer C.

[ritz]

I would beg to defer here...
we know the nbr of ppl who drink, that is 120.
But we do not have any idea as to what is the number of people who neither smoke nor drink.
so the answer should be E

[sukrant26]

OA IS E.....

[xilef]

ok, you are right, it says 'In a survey of 150 persons' and I assumed In a survey of 150 smokers and drinkers.

[humeixia]

The answer is E.