Question

kele fills a bird feeder with seeds. as birds visit the feeder, the height of the seeds changes from 13.6 cm to 11.1 cm over a period of 6\frac{1}{4} hours. what is the average change in the height of the seeds each hour? show your work.
what is - 0.3(0.2)(12)?
math journal write a division expression with fractions that results in -\frac{3}{8}. explain your thinking.
end of lesson checklist
interactive glossary find the entry for rational number. add two important things you learned about rational numbers in this lesson.
self check go back to the unit 3 opener and see what you can check off

Explanation:

Step1: Calculate the total change in height

The total change in height is \(11.1 - 13.6=- 2.5\) cm.

Step2: Convert the mixed - number of time to an improper fraction

\(6\frac{1}{4}=\frac{6\times4 + 1}{4}=\frac{25}{4}\) hours.

Step3: Calculate the average change per hour

The average change per hour is \(\frac{-2.5}{\frac{25}{4}}\). Using the rule \(\frac{a}{b}=a\times\frac{1}{b}\), we have \(-2.5\times\frac{4}{25}\). Since \(-2.5=-\frac{5}{2}\), then \(-\frac{5}{2}\times\frac{4}{25}=\frac{-5\times4}{2\times25}=\frac{-20}{50}=- 0.4\) cm/hour.

Answer:

The average change in the height of the seeds each hour is \(-0.4\) cm/hour.