Chapter 7.5, Problem 15E

To determine

To calculate: To find the percent of change of surface area from $\text{1963}$ to $2001$ .

Answer to Problem 15E

The area of Lake Chad decreased by $91.5\%$

Explanation of Solution

Given information:

Consider the information provided in the question, Original area in $\text{1963}$ : $10000$ square miles and New area in $2001$ : $850$ square miles.

Formula used:

  $\text{percent of change, }p\text{\% =}\frac{\text{Amount of increrase or decrease}}{\text{Original amount}}$

Calculation:

It is observed from the data provided that the, new price in $2001$< original price in $\text{1991}$ , this is a question of percent of increase.

  $\begin{array}{l}\text{percent of change, }p\text{\% =}\frac{\text{Amount of increrase or decrease}}{\text{Original amount}}\\ \text{ = }\frac{\text{Amount of decrease}}{\text{Original Amount}}\text{ [write formula for percent of decrease]}\\ \text{ = }\frac{10000-850}{10000}\text{ [substitute]}\\ \text{ = }\frac{9150}{10000}\text{ [subtract]}\\ \text{ = 0}\text{.9150}=91.5\%\text{ [divide}\text{. Then write decimal as a percent] }\end{array}$

Therefore,

The area of Lake Chad decreased by $91.5\%$