A student conducted an experiment with two identical fish tanks, Tank 1 and Tank 2. About 20 mL of water purifier was added to Tank 1, and 10 mL of water purifier was added to Tank 2. Both tanks were heated to [tex]$88^{\circ} F$[/tex]. The water purity of each tank was tested every day in particles per liter. The purity was recorded over a period of 5 weeks in the table shown below.

\begin{tabular}{|c|c|c|}
\hline Week & Water Purity of Tank 1 & Water Purity of Tank 2 \\
\hline 1 & 12.6 & 12.6 \\
\hline 2 & 13.7 & 13.9 \\
\hline 3 & 14.3 & 14.4 \\
\hline 4 & 15.7 & 15.8 \\
\hline 5 & 17.6 & 17.6 \\
\hline
\end{tabular}

Based on the table, which of these conclusions is correct?

A. Fish need 10 mL of water purifier to survive.
B. More purifier is needed to keep heated water clean.
C. Water purifier can help a fish survive longer.
D. Water purifier keeps fish tanks clearer for longer.



Answer :

Based on the data provided, we observe the water purity in both Tank 1 and Tank 2 over the span of 5 weeks. The recorded water purity values for both tanks show similar trends of increase throughout the weeks. Despite Tank 1 starting with 20 mL of water purifier and Tank 2 starting with 10 mL of water purifier, the purity readings do not show a significant difference in their trends; both tanks demonstrate a comparable increase in water purity.

Let’s analyze the recorded data in detail:

1. Week 1: Both tanks start with the same water purity of 12.6 particles per liter.

2. Week 2: Tank 1 shows a purity of 13.7, while Tank 2 shows a slightly higher purity of 13.9.

3. Week 3: Tank 1 has a purity of 14.3, and Tank 2 has a purity of 14.4, still quite close.

4. Week 4: Tank 1 has a water purity of 15.7, and Tank 2 has a water purity of 15.8, remaining nearly identical.

5. Week 5: Both tanks show a water purity of 17.6, indicating the same level of purity.

The trends suggest that despite the different amounts of water purifier added initially, both tanks display similar patterns in water purity improvement. Therefore, the conclusion drawn from this experiment is that the water purifier effectively keeps fish tanks clearer for longer durations.

Hence, the correct conclusion is:
Water purifier keeps fish tanks clearer for longer.