Answer
$11 \ in $
Work Step by Step
The relationship of two rotating pulleys connected by a belt is:
(diameter of A)(rpm of A) = (diameter of B)(rpm of B).
Now we have
$$
4.0\times 1874=x\times 680\Longrightarrow x=\frac{0.4\times 1874}{680}=11\ in
.$$
