Simplify.
\[
\sqrt{28 s^{5} t}
\]

Assume that all variables represent positive real numbers.
[1]
$\sqrt{\square}$
$\square^{\square}$
x
S

Step 1 ：The given expression is a square root of a product. To simplify this, we can use the property of square roots that the square root of a product is the product of the square roots.

Step 2 ：We can then simplify the square roots of the individual terms. The square root of 28 can be simplified to 2 times the square root of 7.

Step 3 ：The square root of \(s^5\) can be simplified to \(s^2\) times the square root of \(s\). The square root of \(t\) is just \(\sqrt{t}\).

Step 4 ：So, the simplified expression is \(2s^2\sqrt{7s t}\).

Step 5 ：The simplified form of the given expression is \(\boxed{2s^2\sqrt{7s t}}\)