Independent Practice

Question

From 1999 to 2000, the number of days of unhealthy air quality in Charlotte, North Carolina, dropped from 5 to 2. Find the percent of decrease in the number of days of unhealthy air.

A.
15%

B.
1.5%

C.
6%

D.
60%

Answer 1

To find the percent decrease, we can use the formula:

\[ \text{Percent Decrease} = \frac{\text{Old Value} - \text{New Value}}{\text{Old Value}} \times 100 \]

In this case, the old value (number of days of unhealthy air quality in 1999) is 5, and the new value (in 2000) is 2.

1. Calculate the difference: \[ \text{Difference} = 5 - 2 = 3 \]

2. Now, use the formula to calculate the percent decrease: \[ \text{Percent Decrease} = \frac{3}{5} \times 100 = 0.6 \times 100 = 60% \]

Thus, the percent decrease in the number of days of unhealthy air quality is:

D. 60%