Answer:
6.38%
Explanation:
The computation of the stock expected constant growth rate is shown below:
But before that first we have to find out the dividend for each year by considering the growth rate
Dividend for year 1  = $1 × (1 + 0.30) = $1.30
Dividend for year 2 = $1 × (1 + 0.30)^2 = $1.69
Dividend for year 3 = $1 × (1 + 0.30)^3 = $2.197
Dividend for year 4 = $1 × (1 + 0.30)^4 = $2.8561
and, the selling price of the stock is $40
So,
$1.30 × 0.8929 + $1.69 × 0.7972 + $2.197 × 0.7118 + $2.8561 × 0.6355) + [$2.8561 × (1 +X%) ÷ 12% - X%)] = $40
After solving this
The X is 6.38%
And, the discount rate is come from
= 1 ÷ (1 + interest rate)^number of years
Like 0.8929 is come from
= 1 ÷ (1 + 0.12)^1