than and/or

"and" is the correct choice.

This is a tricky question. We all know Tom is the busiest person.

But the correct expression is: Tom is busier than Tim or Chip. You really can't say Tom is busier than Tim and Chip...does it mean Tim and Chip combined?

Take another example. Tom makes $100,000 a year. Tim makes $80,000. Chip $50,000.
Then you would say "Tom makes more money than Tim or Chip." It is als

Mathematicians say:
"X is greater than Y and Z" to mean "(X>Y) and (X>Z)"
"X is greater than Y or Z" to mean "(X>Y) or (X>Z)"

paco

Don't drink or drive. = Don't drink and don't drive.

Don't drink and drive. = Don't drive after you have drunk. (Drinking and driving are combined.)

Russia is bigger than Taiwan or China. = Russia is bigger than Taiwan and Russia is bigger than China.

Russia is bigger than Taiwan and China. = Russia is bigger than Taiwan combined together with China.

In spoken English, you would stress "or":

"If Tom is busier than Tim & Tom is busier than Chip, then Tom is busier than Tim or Chip."

This has the sense "busier than Tim" and "busier than Chip".

But "and" often occurs, in such situations. The context usually resolves any apparent ambiguity.

MrP