The following order book exists for a particular stock. The last trade on the stock was at $42.34

Buy Orders				Sell Orders
Shares		Price		Shares		Price
250		$42.33		100		$42.36
400		42.32		350		42.37
900		42.31		1,000		42.39
225		42.29		200		42.40
				300		42.41

a. If you place a market buy order for 100 shares, at what price will it be filled?

b. If you place a market sell order for 200 shares, at what price will it be filled?