An insulated jug holds 4.5 quarts of water. how many pints is that?

You're talking about units of volume in the US "customary" system.

1 quart = 2 pints
2 quarts = 4 pints
3 quarts = 6 pints
4 quarts = 8 pints
4.5 quarts = 9 pints

It makes no difference what kind of container may surround the quarts,
or what substance may be in them.  The conversion of quarts to pints is
the same, even if the quarts are in outer space and totally empty.

4.5 quarts = 9 pints

( Remember: 1 quart equals 2 pints)