What is the final price if the bid price exceeds the ask price in an order driven market?

How long does a bear market typically last?

about 9.6 months

Bear markets tend to be short-lived.
The average length of a bear market is 289 days, or about 9.6 months. That’s significantly shorter than the average length of a bull market, which is 991 days or 2.7 years. Every 3.6 years: That’s the long-term average frequency between bear markets.