Question

Find the amount of change and the percent of decrease in the number of Hurricanes from 2008 to 2009 and from 2010 to 2011. Compare the amounts of change and the percents of decrease.
PLZ HELP

Answer 1

Well, in the chart for 2008 it has 8 hurricanes, in 2009 it has based on that bar, 3 hurricanes, the change is then 5, 8 - 3  = 5.

now if we take 8 to be the 100%, what is 5 off of it in percentage?

$\bf \begin{array}{ccll} amount&\%\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 8&100\\ 5&p \end{array}\implies \cfrac{8}{5}=\cfrac{100}{p}\implies p=\cfrac{5\cdot 100}{8}\implies p = 62.5$

now in 2010, there were 12 hurricanes, whilst looking at the bar, in 2011 there were only 7, so that's a change of 5.

if we take 12 to be the 100%, what is 5 off of it in percentage?

$\bf \begin{array}{ccll} amount&\%\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 12&100\\ 5&p \end{array}\implies \cfrac{12}{5}=\cfrac{100}{p}\implies p=\cfrac{5\cdot 100}{12}\implies p\approx 41.67$