rahim sets out to cross a forest.on the 1st day, he completes 1/10th of journey. on 2nd he covers 2/3rd of distance travelled 1st day. he continues in this manner alternating the days in which he travels 1/10th the distance still to be covered, with days on which he travels 2/3rd of total distance already covered. at the end of 7th day, he finds that twenty two nd half km more will see the end of his journey. how wide is the forest?

1) 66 2/3 km
2) 100 km
3) 120 km
4) 150 km