Answer: 11.5 million shares
Step-by-step explanation:
The demand for the new shares is 20 million at the IPO price and the company plans to sell 10 million shares only.
Demand therefore exceeds supply so you as the lead underwriter will have to exercise the over-allotment option of 1.5 million additional shares provided to you.
Total shares you allocate will be:
= 10 + 1.5
= 11.5 million shares