'manpreet singh wrote:Q)Santa estimates that 10% of the children in the world have been good this year but do not celebrate Christmas, and that 50% of the children who celebrateChristmas have been good this year. If 40% of the children in theworld have been good, what percentage of children in the world are notgood and do not celebrate Christmas?
How can i do such a problem in less than 2 mins.i hate reading such a long question as it really has bad effect on my speed and flow.need help on this!!
This is an EITHER/OR group question.
Every child is EITHER good OR not good.
Every child EITHER celebrates Christmas OR does not.
For an EITHER/OR group problem, use a GROUP GRID to organize the data.
Let G = good, NG = not good, C = celebrates, DC = doesn't celebrate.
Here's the grid, with 100 children plugged in for the total.
_______________G______NG_______Total
C:
DC:
total:___________________________100
Now let's use the information in the problem to complete the grid step by step.
As soon as we know 2 entries in a row or a column, we can calculate the remaining entry in that row or column.
10% of the children in the world have been good this year but do not celebrate Christmas:
_______________G______NG_______Total
C:
DC:____________10
total:____________________________100
50% of the children who celebrate Christmas have been good this year.
Since we don't yet know how many celebrate Christmas, hold onto this information.
40% of the children in the world have been good:
_______________G______NG_______Total
C:_____________30
DC:____________10
total:___________40______60_______100
Now let's return to the information we skipped over:
50% of the children who celebrate Christmas have been good this year.
Since 30 children who celebrate Christmas have been good, the total number who celebrate Christmas = 60:
_______________G______NG________Total
C:_____________30______30_________60
DC:____________10______30_________40
total:___________40______60________100
Now we can answer the question:
Not good and do not celebrate = 30.
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