Tagger wrote:

Still can't get the solution using the Double matrix

Please help !

Take a look at the image.

X is the percentage of Non-Window, and we know that 25% of that number has Hardwood => 0.25x is in the cell (NW, H) and 0,75x is, of course, in the (NW, NH) cell.

(

0.25x+0.75x=x). The tot Hardwood is 60%, and is composed by the first row:

50+0.25x=60 x=40. Ok, we have X, or the tot perc of NonWindows.

Now we know also that

y+40%=100% and clearly y = 60% => tot perc of W is 60%.This is composed by the cell [Window, Hardwood (50%)] and by the cell [Window, NonHardwood (that must be 10% since 50%+10%=60%)]

And now we have all the data we can have. To answer the question: "what percent of the apartments with windows have hardwood floors?" we must calculate the fraction (apartments with windows and hardwood floors [W,H])/(apartments with windows[W]) =

\frac{50%}{60%} =

83 \frac{1}{3}Hope it's clear

Attachments

matrix.png [ 2.63 KiB | Viewed 1889 times ]

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