Problem
A group of 9 friends invest equally in a business opportunity that costs $20,000. If n more friends were to take part evenly in the investment...
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So What?
Math questions involving two equations and two unknowns can usually be combined into one equation with one unknown.
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ACT: Science Question #2 |
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Passage 1
Various methods are used to estimate the number of microorganisms in a culture. One method utilizes a spectrophotometer to measure the density of organisms in a broth medium. Density indicates the quantity of organisms in a given volume.
In this method, a beam of light is passed through the broth medium. The density of microorganisms in the broth is inversely proportional to the intensity of the light that passes through the broth. A meter is used to indicate the percentage of light transmitted through the medium.
The spectrophotometric data are used to produce a graph, such as the one below, that relates optical density to cell number.
Question:
In Figure 2, an optical density of 0.9 coincides with a cell number of approximately:
Choices:
The correct answer is C.
Questions like these just ask you to look up information in a graph.
| Reading across from the y-axis at an optical density value of 0.9, |
| the curve intersects at a cell number of |
4 |
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108
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