Consider the following stocks in a portfolio

Stock	Amount Invested	Beta
1	$500,000	0.6
2	500,000	1.0
3	500,000	1.4
4	500,000	1.8

The risk-free rate is 6 percent and the portfolio's required rate of return is 12.5 percent. You want to sell all of your holdings of Stock 1 and use the proceeds to purchase more shares of Stock 4 (i.e., the amount of fund previously invested in stock 1 is now invested in stock 4). What would be the portfolio's required rate of return following this change?

Please show all working. Thanks!