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GMAT Math Probability question... please advise. thanks


vini1900

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In a graduation class of a certain college 48% of students are males and 52% are females. In this class 40% of the males and 20% of the female students are 20 yrs or older. If one student in the graduating class is randomly selected approximately, what is the probability that he or she will be less than 25 yrs old?

 

A) 0.90

 

B) 0.70

 

C) 0.45

 

D) 0.30

 

E) 0.25

 

Thanks!

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So, 40% of the 48% that are males are 25 or over and 20% of the females. 0.48*0.4+0.52*0.2 = .296. This is the total percentage that is 25 or older. That means that 1-.296 are then 25, or about .7.

 

Because the answers are so spread out on this question I would probably just approximate and multiply .5*.4 and .5*.2 to get 30% and get the 70% from there.

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