IXL - Estimate population size using proportions (Algebra 1 practice)

Anthony is starting his own beehive so that he can have fresh honey straight from the hive. Anthony decides to check the current population of bees in the hive by marking 39 bees with special bee-marking paint. Later, Anthony collects 220 bees and observes that 22 of them are marked. To the nearest whole number, what is the best estimate for the bee population?

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question

Jerry studies bottlenose dolphins and wants to estimate the population in a certain region. Jerry catches 170 dolphins, marks them, and releases them. Later on, Jerry catches 240 dolphins and observes that 12 of them are marked. To the nearest whole number, what is the best estimate for the dolphin population?

solution

The ratio of marked dolphins to total dolphins should be about the same in both the sample population and the overall population. You know how many dolphins were in the sample and how many of those were marked. You also know the total number of marked dolphins.

Set up a proportion.

marked dolphins counted

total dolphins counted

total marked dolphins

estimated dolphin population

Plug in the numbers you know and solve for the dolphin population,

240

170

240

(

240

)

Multiply both sides by

240

170

(

240

)

Multiply both sides by

240

Simplify

170

240

Simplify

40,800

Simplify

Divide both sides by 12

3,400

Divide both sides by 12

The best estimate for the dolphin population is 3,400.

Looking for more? Try these:

Lesson: Proportions

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Teacher tools

Work it out

Not feeling ready yet? These can help:

G.1Solve proportions

L.11Do the ratios form a proportion: word problems

Lesson: Proportions

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