Mahesh is going towards East. If he has to go towards North, which of the…
2013
Mahesh is going towards East. If he has to go towards North, which of the following options should he NOT choose?
- A.
right, right, left, right, right
- B.
right, right, left, left, left
- C.
right, right, right
- D.
right, left, right, left
Attempted by 7 students.
Show answer & explanation
Correct answer: D
Treat each 'right' as a 90 degrees clockwise turn and each 'left' as a 90 degrees turn the other way. Starting while facing East, the net turning of a full sequence decides the final direction.
From East, ending up facing North needs a net turn equal to one left turn (which is the same as three right turns).
Sequence right, right, left, right, right: the turns add up to a net of three rights, taking him from East to South to West to North - he faces North.
Sequence right, right, left, left, left: the rights and lefts combine to one net left, taking him from East to North - he faces North.
Sequence right, right, right: from East, three rights go South, West, North - he faces North.
Sequence right, left, right, left: every right is cancelled by the left that follows it, so the net turn is zero and he still faces East - this one never reaches North.
So the sequence he should NOT choose is right, left, right, left.