Estimating Population Sizes

At a farm there were 7 cows for every 2 horses. If there was 21 cows estimate how many horses there would be?

• 9

• 3

• 6

• 14

What would be the population in this example?
Surveyors in a mall choose shoppers to ask about products they prefer.

• the surveyors

• all shoppers in the mall

• the shoppers who were asked their preferences

A worker at a local aquarium is instructed to estimate the population of sardines in the tank. She catches 170 sardines, marks them with special paint, and returns them to the tank. Then she catches 330 sardines and finds that 17 of them are marked. To the nearest whole number, what is the best estimate for the sardine population?

• 3200 sardines

• 3300 sardines

• 3500 sardines

• 3600 sardines

A jar contains 1,800 marbles. James enters a contest to guess the number of any one color of marbles in the jar. He is allowed to take 4 random samples of 200 marbles each. Approximately how many red marbles can he expect are in the jar?

• 500

• 525

• 550

• 600

A researcher who was conducting a study caught, tagged, and released 35 opossums. Weeks later, the researcher caught a total of 360 opossums, of which 14 were tagged. To the nearest whole number, what is the best estimate for the opossum population?

• 800 opossum

• 900 opossum

• 850 opossum

• 875 opossum

7.SP.1

• A

• B

• C

• D

You ask 75 randomly chosen students at a school how many movies they watch each week. If there are 1200 students in the school, estimate the number of students who watch one movie per week.

• 900

• 210

• 840

• 336

Some researchers wanted to monitor the trout population, so they marked 830 trout with tags. Later, they captured 720 trout and found that 72 of them had tags. To the nearest whole number, what is the best estimate for the trout population?

• 8300 trout

• 8100 trout

• 7900 trout

• 8200 trout

Darrien surveys 60 of the actors theater class. He concludes that 8 out of 15 actors have previous acting experience. What is the sample size?

• 60

• 8

• 15

• 53

How could Javier decrease the margin of error?

• Increase the sample size

• Decrease the sample size