This workout asks us to use the information in the order book below and calculate the average price that will result from the given order. So if we start by looking at the existing order book, we've got the buy orders on the left-hand side and the buy orders are arranged with the highest prices first. On the right-hand side, we have the sell orders and they're arranged with the lowest prices first.

Looking now at the order type that we have, this is a limit order. It is a sell order. The size is 5,200. So if we were looking at shares, 5,200 shares. And the price is 343. Now, remember that a limit order guarantees the execution price to be equal to or better than the limit price that has been set which in this case is 343. Now, as this is a sell order, we need to look at the buy side of the order book to satisfy this order.

To work out the average trade price, we first need to work out the value of the total trade. Then we can divide by the total number of shares that were traded to come up with the average price. So to work out the total trade value, I'm looking at that 343 price limit. And looking at the buy side of my order book, I can see that only the top two orders satisfy this price limit. Because it is a sell order, we don't wanna sell for less than 343 and so only a price of 345 and 344 will do.

So looking at the value of the total trade, that would be equal to the 1,500 shares at a price of 345 plus the 2,700 shares at a price of 344.

That would give us the value of the total trade, but we want an average price per share. So we've gotta take our total value. Just gonna put brackets around that and we need to divide that by the total number of shares that were traded, which is the 1,500 plus the 2,700 and that gives us an average trade price of 344.4.

Next, we're asked to calculate the number of unmatched shares. So this order was to sell 5,200 shares. We sold 1,500 at 345. We sold 2,700 at 344, and that's where we had to stop because the other prices were below the limit of 343. So that then leaves us with an unmatched order of 1,000.

And that 1,000 would go onto the sell side of the order book as it is an unmatched sell order. So to sum up with a limit order, you are guaranteed an execution price at or better than your limit, but you are not guaranteed to execute the full trade, which has happened here, we have 1,000 unmatched shares.