Question

A square field measures $10$ meters by $10$ meters. Ten students each mark off a randomly selected region of the field; each region is square and has side lengths of $1$ meter, and no two regions overlap. The students count the earthworms contained in the soil to a depth of $5$ centimeters beneath the ground's surface in each region. The results are shown in the table below.
Which of the following is a reasonable approximation of the number of earthworms to a depth of $5$ centimeters beneath the ground's surface in the entire field?

• A. $150$
• B. $1,500$
• C. $15,000$
• D. $150,000$

Answer 1

Answer: (C)

Since we have a square field of side $10$ meter, and one region is a smaller square of side $1$ meter, there would be $100$ such regions in the entire field.

Since the analysis is available for $10$ regions, it would be a good approximation to multiply the total number in these ten regions by $10$ to get the total number of earthworms in the field.

We thus add up the obtained figures.

$\Rightarrow 107+147+146+135+149+141+150+154+176+166=1471$

$\Rightarrow 1471\times 10=14710$, can be approximated to an order of $15000.$