A biologist is conducting research on four different types of fish found in a local lake. The numbers of each type are shown in the table.

A table shows the number of fish found in a location. There were ninety small-mouth bass found, two hundred eighty crappies found, sixty sunfish found, and one hundred twenty yellow perch found.

She plans to use a stratified sampling method in which twenty percent of the total population is included in the studies. How many yellow perch will be in her sample?
Answer

twenty-four

twelve

eighteen

6

Question

A biologist is conducting research on four different types of fish found in a local lake. The numbers of each type are shown in the table.

A table shows the number of fish found in a location. There were ninety small-mouth bass found, two hundred eighty crappies found, sixty sunfish found, and one hundred twenty yellow perch found.

She plans to use a stratified sampling method in which twenty percent of the total population is included in the studies. How many yellow perch will be in her sample?
Answer
		
twenty-four
		
twelve
		
eighteen
		
6

directrix · Answer

twenty-four
------------

There are 550 fish in the location of which 120 are yellow perch.
Yellow perch make up 120/550 of the total fish found.

If 20% of the total found fish are to comprise the sample, then 20% of 550 or 110 fish will be in the sample. The number of yellow perch in the sample is given by the proportion:

120/550 = x / 110 where x is the number of yellow perch in the sample
Solving for x yields 24 yellow perch.