10. (Difficult) In a two-period binomial tree, let the volatility at any node be given by...

10. (Difficult) In a two-period binomial tree, let the volatility at any node be given by

where u and d are as usual, respectively, the up-shift and down-shift values for stock price moves on the tree. Given a starting stock price of $50, suggest one way to draw a two-period recombining stock tree when the volatility of the first period is and in the second period is 0.25.