You observe the order book for shares of FB looks as follows:
Asks (volume x price):
100 x 24.63
200 x 23.62
100 x 22.28
50 x 21.71
Bids (volume x price):
100 x 19.28
200 x 18.57
250 x 17.94
200 x 16.63
You want to immediately sell 500 shares of FB on the market. What will be your average price per share?