Answer
pH = 12.95
Work Step by Step
1. Since $Sr(OH)_2$ is a strong base, and it has 2 $OH^-$ in each molecule:
$[OH^-] = 2 * [Sr(OH)_2] = 2 * 0.045 = 0.090M$
2. Calculate the pOH, and then the pH value:
$pOH = -log[OH^-]$
$pOH = -log( 0.090)$
$pOH = 1.05$
$pH + pOH = 14$
$pH + 1.05 = 14$
$pH = 12.95$
