Mark$$s portfolio consists of three stocks: GOOG, $50\%,$ beta $1\mathrm{.}05$; COST, $30\%,$ beta $0\mathrm{.}75$; and BAC, $20\%,$ beta $1\mathrm{.}42.$ Compute Mark$$s portfolio beta.

Group of answer choices

$0\mathrm{.}92$

$1\mathrm{.}03$

$1\mathrm{.}20$

$1\mathrm{.}16$