When you sell the first mining stock you end up with a 90k portfolio with a beta of 1,115 , adding the steelstocks should put you at 1,225 for the overall portfolio. Mind you its been 15 years since I did this, and I have no calculator here. ))

You hold a diversified portfolio consisting of many different common stocks with a total market value of $100,000. The portfolio beta is equal to 1.15. You have decided to sell one of your stocks, a lead mining stock whose beta is equal to 0.8 , for $10,000 net and to use the proceeds to buy $10,000 of stock in a steel company whose beta is equal to 1.9 . What will be the new beta of the portfolio?