In a senior class, 72%

[NMencia09]

In a senior class, 72% of male students and 80% of female students have applied to college. What fraction of the senior class is male?

1) 840 students in sr. class
2) 75% of students in sr. class have applied to college/

OA is B

Anyone know a shortcut how to do this without the diagrams/algebra?

[ShyT]

The questions is asking for what % of senior class is male. To find that out you need to know the relationship between either # of male students to female students or their weighted average. Their weighted average would give you a relationship of proportion male students to female (not actual #) but that is ok because questions asks for fraction of students. (which is same as proportion) (%,fraction and proportion is all the same)

If 72% of male students and 80% female. and combined 75% overall that means that. 80-72=8 units apart. if it was half girls half boys the % of overall students would be simple avg formula (72+80)/2 which is 76%. so there is slightly more males than females because its at 75% actually a male to female poportion of 5:3 or 5/8 of total class.

long story short you really shouldn't have to do this algebra because you should understand the rules of weighted averages. that if a % of x combined with % of y gives a new %. That new % shows the (weighted relation.. or fraction or proportion all the same) between the x&y.
This is more of an understanding the concept DS problem than actually having to work it out. So if you are still struggling I would simply review the concept of weighted averages and how they work.
This question shouldn't take you longer than 20 seconds because you shouldn't have to try to work it out. B and move on.

[RonPurewal]

please search the forums, folks -- thanks

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