In a city where all streets run east-to-west, all avenues run north-to

She choose a route which allows her to walk fewest number of blocks
there are 2 blocks she will cross towards east moves represented by E,E and there will be 5 blocks she will cross towards south represented by S,S,S,S,S

total number of ways \(\frac{7!}{5!2!}\)

there are 4 ways she can cross 2 blocks on av.1 as shown in attached image.


4/21 is Answer .

in order to reach from black dot to blue dot she has to make 1 E and 3 S moves .. total 4!/3! = 4Ways . now from Blue dot to Maroon dot there is only 1 way . so there are only 4 ways .


A

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