Please answer the weight for BRK/A, SPX, NDX, and RUT step by step. Thanks!

YEAR BRK/A SPX NDX RUT 21.4 15.1 19.22 26.85 -4.7 2.1 2.7 -4.18 2010 2011 2012 2013 2014 16.B 16 16.82 16.35 32.7 32.4 34.99 38.82 27 13.7 17.94 4.89 2015 -12.5 1.4 8.43 -4.41 2016 23.4 12 5.89 21.31 2017 21.9 21.8 31.52 14.65 2018 2.8 -4.4 -1.04 - 11.01 2019 11 31.5 37.96 25.52 Assuming there is no risk-free asset available, suppose you desire to invest in a portfolio of these 4 risky assets such that you minimize the portfolio variance, subject to the constraint that the portfolio weights sum to 1. Note that short positions (negative weights) are permissible. Using mean-variance portfolio optimization, determine the 4 minimum variance portfolio weightings and the minimum portfolio variance. Please enter your solutions in the answer boxes for Questions 1 to 5. What is the portfolio weight for BRK/A? Please express your numerical answer in decimal (not percentage) form and round your answer to two decimal places. YEAR BRK/A SPX NDX RUT 21.4 15.1 19.22 26.85 -4.7 2.1 2.7 -4.18 2010 2011 2012 2013 2014 16.B 16 16.82 16.35 32.7 32.4 34.99 38.82 27 13.7 17.94 4.89 2015 -12.5 1.4 8.43 -4.41 2016 23.4 12 5.89 21.31 2017 21.9 21.8 31.52 14.65 2018 2.8 -4.4 -1.04 - 11.01 2019 11 31.5 37.96 25.52 Assuming there is no risk-free asset available, suppose you desire to invest in a portfolio of these 4 risky assets such that you minimize the portfolio variance, subject to the constraint that the portfolio weights sum to 1. Note that short positions (negative weights) are permissible. Using mean-variance portfolio optimization, determine the 4 minimum variance portfolio weightings and the minimum portfolio variance. Please enter your solutions in the answer boxes for Questions 1 to 5. What is the portfolio weight for BRK/A? Please express your numerical answer in decimal (not percentage) form and round your answer to two decimal places