Ok so im a little stressed out I have an exam on thurs and no idea about this stuff. This was the example on the practice examination! HELP
scientists believe that 40% of industries are heavy polluters. They found that 30 out of 80 are heavy polluters.
ok so here is what i need help with,
What is the variable?
what hypothesis test do i need to do??
and if i have a 95% confidance interval, (standard error of 0.05), what sample size do i need??