Chapter 8.1, Problem 41IP

To determine

Summer sleeping heart rate

Answer to Problem 41IP

The summer sleeping heart rate is $x=70$ .

Explanation of Solution

Given:

The sleeping heart rate of a black bear during hibernation is about $\frac{2}{5}$ of its summer rate and the sleeping heart rate of a bear is $28$ beats per minutes during hibernation

Concept Used:

• To get rid of a number in addition from one side, subtract the same number from both sides of equal sign.
• To get rid of a number in subtraction from one side, add the same number both sides of equal sign.
• To get rid of a number in multiplication from one side, divide the same number from both sides of equal sign.
• To get rid of a number in division from one side, multiply the same number both sides of equal sign.

Rules of Addition/ Subtraction:

• Two numbers with similar sign always get added and the resulting number will carry the similar sign.
• Two numbers with opposite signs always get subtracted and the resulting number will carry the sign of larger number.

Rules of Multiplication/ Division:

• The product/quotient of two similar sign numbers is always positive.
• The product/quotient of two numbers with opposite signs is always negative.

Calculation:

In order to find the equation, Let x be the summer sleeping heart rate

Sleeping rate of bear during hibernation is $\frac{2}{5}x$

Sleeping heart rate is $28$

Thus, the an equation as $\frac{2}{5}x=28$

Then find the value of x as below:

  $\begin{array}{c}\frac{2}{5}x=28\\ \frac{2}{5}x\times 5=28\times 5\\ 2x=140\\ \frac{2x}{2}=\frac{140}{2}\\ x=70\end{array}$

Thus, the summer sleeping heart rate is $x=70$ .