Over North's 1♠ East has a risky 2♦ overcall.

West should raise to the level of the fit. Partner has 5+ cards for overcall, with west's own 5 card suit he should bid to make 10 tricks by bidding 4♦ . Some norths may bid 4♥  (converted to 4♠  by south) or 4♠ directly.

Part scores are crucial in duplicate (less so in teams). All contracts and scores different on this board.

West will pass unless partnership agreement is for a weak 5 card suit or playing the old Lucas 2s.(see this page for more information 

North will pass over both possibilities.

East over 2 passes has a difficult call, whether to open a balanced 11HCPs with only minors opposite a passed partner.  Probably best to pass.

If East passes South should probably open 1♠ (meeting the rule of 15 - HCPs + length of spade suit.

North will bid 2♠ s which will be passed out.

If West opens a weak 2♥ s they will probably buy the contract.