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Tough problem. Does anyone have the answer? It says D.
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mcmoorthy
Hi the27s,

I think the answer should be A.

The question asks Area of ADB/Area of ABC.

Area of ADB = 1/2 * BD * p

Area of ABC can be split as Area of ADB + Area of DBC

Which is 1/2 * BD * p + 1/2 * BD * q

Simplifying this becomes 1/2 * BD (p +q)

Now the ratio becomes 1/2 * BD * p/(1/2*BD(p+q))

Cancelling 1/2 * BD in the numerator and denominator the ratio becomes
p/(p+q)

Now statement 1 gives p = 9q

The ratio of areas of ADB/ABC = 9q/(9q+q) = 9/10

Statement 2 : insufficient.

Answer: A

Posted from my mobile device

Nice. Why isn't B sufficient?
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CEdward
Tough problem. Does anyone have the answer? It says D.
Answer is indeed D
B is also sufficient.
triangle ABD and BDC are similar.
AC 10, AB 3√10 so BC √10

By similar traingle we can calculate the height if both traingles in terms of P and Q.
thus we can get the desired area ratio

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mcmoorthy
Hi the27s,

I think the answer should be A.

The question asks Area of ADB/Area of ABC.

Area of ADB = 1/2 * BD * p

Area of ABC can be split as Area of ADB + Area of DBC

Which is 1/2 * BD * p + 1/2 * BD * q

Simplifying this becomes 1/2 * BD (p +q)

Now the ratio becomes 1/2 * BD * p/(1/2*BD(p+q))

Cancelling 1/2 * BD in the numerator and denominator the ratio becomes
p/(p+q)

Now statement 1 gives p = 9q

The ratio of areas of ADB/ABC = 9q/(9q+q) = 9/10

Statement 2 : insufficient.

Answer: A

Posted from my mobile device

B is also sufficient. Since triangle ABD and ABC are similar, therefore the ratio of areas of these triangles is equal to the ratio of squares of the sides of these triangles.

Hence ratio of areas of ABD and ABC= (AB^2/AC^2)
Since AB=3*sqrt10 and AC=10
Therefore ratio of areas of ABD and ABC = 9/10

Therefore answer is D.
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