A marine biologist measures the density of oyster larvae, in number of larvae per liter of seawater, at four different sites in a coastal habitat over three days. The table below shows her results.

Population Density
\begin{tabular}{|l|c|c|c|c|}
\cline { 2 - 5 } \multicolumn{1}{c|}{} & Site [tex]$W$[/tex] & Site X & Site Y & Site Z \\
\hline Day 1 & 40 & 22 & 0 & 7 \\
\hline Day 2 & 3 & 1 & 14 & 26 \\
\hline Day 3 & 2 & 6 & 3 & 1 \\
\hline
\end{tabular}

Which distribution pattern do the oyster larvae exhibit?

A. stationary
B. random
C. clumped
D. uniform



Answer :

To determine the distribution pattern of oyster larvae across four different sites over three days, we begin by calculating the mean density and variance of the larvae density at each site. Distribution patterns can often be inferred from the variance, where high variance might suggest a clumped distribution.

Let's break down the calculations step-by-step:

### Step 1: Compute the Mean Density

We calculate the mean density for each site (W, X, Y, Z) across the three days.

Site W:
[tex]\[ \text{Mean Density (W)} = \frac{40 + 3 + 2}{3} = \frac{45}{3} = 15.0 \][/tex]

Site X:
[tex]\[ \text{Mean Density (X)} = \frac{22 + 1 + 6}{3} = \frac{29}{3} \approx 9.67 \][/tex]

Site Y:
[tex]\[ \text{Mean Density (Y)} = \frac{0 + 14 + 3}{3} = \frac{17}{3} \approx 5.67 \][/tex]

Site Z:
[tex]\[ \text{Mean Density (Z)} = \frac{7 + 26 + 1}{3} = \frac{34}{3} \approx 11.33 \][/tex]

### Step 2: Compute the Variance

Next, we calculate the variance for each site, which measures how much the densities at each site vary from their respective means.

Site W:
[tex]\[ \text{Variance (W)} = \frac{(40 - 15)^2 + (3 - 15)^2 + (2 - 15)^2}{3} = \frac{625 + 144 + 169}{3} = \frac{938}{3} \approx 312.67 \][/tex]

Site X:
[tex]\[ \text{Variance (X)} = \frac{(22 - 9.67)^2 + (1 - 9.67)^2 + (6 - 9.67)^2}{3} = \frac{153.51 + 75.11 + 13.44}{3} \approx 80.22 \][/tex]

Site Y:
[tex]\[ \text{Variance (Y)} = \frac{(0 - 5.67)^2 + (14 - 5.67)^2 + (3 - 5.67)^2}{3} = \frac{32.11 + 69.44 + 7.11}{3} \approx 36.22 \][/tex]

Site Z:
[tex]\[ \text{Variance (Z)} = \frac{(7 - 11.33)^2 + (26 - 11.33)^2 + (1 - 11.33)^2}{3} = \frac{18.78 + 214.78 + 106.78}{3} = 113.56 \][/tex]

### Step 3: Interpret the Variances

We analyze the variances to infer the distribution pattern:

- Site W: 312.67
- Site X: 80.22
- Site Y: 36.22
- Site Z: 113.56

A high variance often suggests a clumped distribution because there are larger discrepancies in the density readings.

### Conclusion

Given the variances at the different sites, particularly the highest variance being 312.67 at Site W, it can be inferred that the distribution pattern of the oyster larvae is clumped.

Thus, the answer is:

C. clumped