An environmental scientist obtains a sample of water from an irrigation canal that contains a certain type of bacteria at a concentration of 2 per milliliter. Find the standard deviation of the number of Bacteria in a 4-milliliter sample.
A) 8
B) 1.4
C) 2.8
D) 2

Question

Quizplus · Accepted Answer

We know that the standard deviation formula is:

standard deviation = square root of [(Σ(x - μ)^2)/N]

Where Σ is the sum, x is the individual value, μ is the mean, and N is the sample size.

In this case, we want to find the standard deviation of the number of bacteria in a 4-milliliter sample, which is a larger sample than the original one. We can use the formula:

standard deviation = square root of [(Σ(x - μ)^2)/N]

where x = number of bacteria in each milliliter, μ = 2 (since that's the concentration of bacteria in the original sample), and N = 4 (since that's the size of our new sample).

Let's first calculate the sum of (x - μ)^2:

(0 - 2)^2 + (2 - 2)^2 + (4 - 2)^2 + (6 - 2)^2 = 16

Now we can plug this into the formula:

standard deviation = square root of [(Σ(x - μ)^2)/N] = square root of (16/4) = square root of 4 = 2

Therefore, the answer is (C) 2.

An Environmental Scientist Obtains a Sample of Water from an Irrigation