What is one possible explanation as to why tryptophan makes you sleepy?

Arecent poll of 500 residents in a large town found that only 36% were in favor of a proposed referendum to build a new high school. find the margin of error for this poll if we want 95% confidence in our estimate of the percentage of residents in favor of this proposed referendum.

The american public was excited by the invention of the railroad system. true false

What agreement did britain and the united states make in the treaty of 1818