Chapter 17.1, Problem 6R

To determine

To Compare: The mass of the new penny with that of the old penny.

Answer to Problem 6R

The new penny’s mass is 19% less than the old penny’s mass.

Explanation of Solution

Given info:

The old mass of the penny is, $m_{old}=3.1\text{g}$

The new mass of the penny is, $m_{new}=2.5\text{g}$

Formula used:

The mass percentage is given as,

  $\text{mass}\%=\frac{\text{change}\text{in}\text{mass}}{\text{old}\text{mass}}\times 100=\frac{\Delta m}{m_{old}}\times 100$

Calculation:

Now substitute the value of masses in the above formula

  $\begin{array}{l}\text{mass\%}=\frac{\Delta m}{m_{old}}\times 100\\ =\frac{m_{old}-m_{new}}{m_{old}}\times 100\\ =\frac{3.1g-2.5g}{3.1g}\times 100\\ =19\%\end{array}$

Conclusion:

Hence, the mass of the new penny is 19% less than the old penny’s mass.