Assume that $\mathrm{a}< \mathrm{b}$ and $\mathrm{c}< 0$. State whether the following statement is true or false
\[
a c> b c
\]

Step 1 ：Assume that \(abc\).

Step 2 ：This is a question about the properties of inequalities. When we multiply or divide both sides of an inequality by a positive number, the direction of the inequality remains the same. However, when we multiply or divide both sides of an inequality by a negative number, the direction of the inequality changes.

Step 3 ：Since \(c\) is less than 0, it is a negative number. Therefore, when we multiply both sides of the inequality \(a < b\) by \(c\), the direction of the inequality should change.

Step 4 ：So, the statement \(ac > bc\) should be true.

Step 5 ：Final Answer: The statement \(ac > bc\) is \(\boxed{true}\) when \(a < b\) and \(c < 0\).