If the Formula for the variance of volatility in the returns a portfolio of 2 shares is as follows:

2=(22+(1)22+2(1))

where

= standard deviation of returns to portfolio

= standard deviation of returns to Vodafone shares

= standard deviation of returns to BP shares

= the proportion we invest in Vodafone

(1) = the proportion we invest in BP

= The correlation coefficient between returns on the two shares

Then if:

=0.35

=0.4

=0.3

What is the value of that minimises the variance in this portfolio?