Researchers make a one-sample z interval to estimate the proportion of adults who would say they learned something new in the past month. Previous studies have suggested that about 40% would answer "yes" to this
question. The researchers plan on using a confidence level of 95%, and they want the margin of error to be no
more than 25%.

Jeffery conducted a survey in his school and found that 30 of the 50 eighth grade students' favorite subject is mathematics. based on the results, jeffery concluded that out of the 200 students in his school, 120 students' favorite subject is mathematics. select the statement that is true about jeffery's conclusion. a. jeffery's conclusion is not valid because the sample was biased since only 200 students were surveyed. b. jeffery's conclusion is valid because the sample was random since all of the students were eighth grade students. c. jeffery's conclusion is valid because the sample was random. d. jeffery's conclusion is not valid because the sample was biased since all of the students were eighth grade students.

Find the greatest common factor of -30x 4 yz 3 and 75x 4 z 2.

45% of the trees in a park are apple trees. there are 27 apple trees in the park. how many trees are in the park in all?