The figure above shows a construction plan for the intersect

Seems a very basic question, but what other possible concepts are tested here? The official explanations was pretty convoluted had a parallelogram and all of that.

Bunnel

I have small doubt here

Suppose the length is not 0 then you will have two variables and you cannot solve the equation i.e the equation becomes

Suppose width=X

Then T= 360-3X-R-S

and here you have 2 variables and 1 equation you cannot get a single solution

Am i right?

No you are not. The edges of the road are parallel, so there is 0 degree angle between them.

Thanks Bunnel Got it

Bunuel - can you please elaborate it further ? why do we need to make this assumption ?

Regards.

Go thru the file attached. Then you will understand the point which Bunuel is making.

Regards,

Abhijit

Hi Guys,

I assumed Angle R = Angle S due to the parallel lines property. Hence for me each statement was sufficient. Why is R not equal to S?

Because the two parallel lines you considered are not cut by the same traversal. So angle R is not equal to angle S.

Also note that in DS questions, the two statements never contradict each other. If you had assumed that angle R = angle S, the two statements should have told you that that is not true.
Statement 1 tells you that angle R is 140. According to you, then angle S should be 140 too. But statement 2 tells you that angle S is 160. This means there is something wrong in your assumption.

Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.



The figure above shows a construction plan for the intersection of three straight roads, each having parallel edges and each having the same width. what is the value of t?

(1) r = 140
(2) s = 160

From the original condition, we can see that there are 3 variables (r,s,t), and one equation (r+s+t=360), so we need 2 more equations, which are given from the 2 conditions, so there is high chance (C) will be our answer.
Looking at the conditions together, r+s+t=140+160+t=360, so it answers the question 'yes', and the answer becomes (C).

For cases where we need 2 more equation, such as original conditions with “2 variables”, or “3 variables and 1 equation”, or “4 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 70% chance that C is the answer, while E has 25% chance. These two are the majority. In case of common mistake type 3,4, the answer may be from A, B or D but there is only 5% chance. Since C is most likely to be the answer using 1) and 2) separately according to DS definition (It saves us time). Obviously there may be cases where the answer is A, B, D or E.

Can you please explain how to answer this question?

[quote="Bunuel"]
The figure above shows a construction plan for the intersection of three straight roads, each having parallel edges and each having the same width. what is the value of t?

(1) r = 140. Not sufficient.
(2) s = 160. Not sufficient.

(1)+(2) Consider the width of the roads to be 0 as shown below:From the figure we have that r+s+t=360 degrees --> 140+160+t=360 --> t=60 degrees. Sufficient.

I cannot understand the thinking process that results in witdth=0 can someone elaborate?

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