SOLUTION

In a certain class, one student is to be selected at random to read. What is the probability that a boy will read?

(1) Two-thirds of the students in the class are boys. Directly gives us the probability of selecting a boy. Sufficient.
(2) Ten of the students in the class are girls. Clearly insufficient.

Answer: A.
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Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.

In a certain class, one student is to be selected at random to read. What is the probability that a boy will read?

(1) Two-thirds of the students in the class are boys.
(2) Ten of the students in the class are girls.


In general, when one con is number and the other con is ratio, it is most likely that ratio is an answer. Also, since fraction=proability, que:probability and in 1) 2/3:fraction. Therefore, the answer is A.


-> from con 1) and con 2), if one of the conditions is given by numbers and the other is given by ratio (percent,fraction), then the condition with ratio (percent,fraction) value has higher chance of being the answer.
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Hi!

This may sound stupid to ask, but are we not assuming that the student we pick can read? I mean, I could not see anywhere in the stem that says the student we pick is capable of reading.
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Thanks Bunuel for the answer!

Its just that this is a DS question. I marked it as E since I thought some of the students can't read. Maybe this happened since I have a young son whom I am still not able to teach how to read

I get it now. Its safe to assume everyone can read.


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Two-thirds of the students in the class are boys. S1 gives the desired outcome/total possibilities as 2/3. So clearly sufficient.

Statement 2 gives no clue abt the total students or the number of boys. Insufficient.

Ans:A