To calculate the percent decrease in the amount of water in the tank, you can use the formula:
\[ \text{Percent Decrease} = \left( \frac{\text{Initial Amount} - \text{Final Amount}}{\text{Initial Amount}} \right) \times 100 \]
In this case, the initial amount of water is 6 inches and the final amount is 3 inches. Plugging in these values:
\[ \text{Percent Decrease} = \left( \frac{6 , \text{in.} - 3 , \text{in.}}{6 , \text{in.}} \right) \times 100 \]
Calculating the difference:
\[ 6 , \text{in.} - 3 , \text{in.} = 3 , \text{in.} \]
Now substitute this value back into the formula:
\[ \text{Percent Decrease} = \left( \frac{3 , \text{in.}}{6 , \text{in.}} \right) \times 100 \]
This simplifies to:
\[ \text{Percent Decrease} = \left( 0.5 \right) \times 100 = 50% \]
Thus, the percent decrease in the water in the tank is 50%.