Do on paper please:

Let the six$-$month interest rate be $8\%.$ To satisfy no$-$arbitrage, assume the six month

rate moves up or down by $25$ bp each six$-$month period with equal probability. Build

an interest rate tree and value a two$-$year, $8\mathrm{.}2\%$ callable bond that can be called for par

$($$$100).$ What is the value of the embedded option?