languid
Definition: (adjective) without energy; slow, sluggish, listless.
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Problem
A palindrome is a positive integer that reads the same forward as it does backwards. If neither the first nor last digit of a palindrome can be zero, how many three-digit palindromes are there?
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ACT: Science Question #3 |
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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:
| Based on the graph, the optical density for a cell number of |
| 15.0 |
× |
108
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would fall between which two values? |
Choices:
The correct answer is C.
Questions like these just ask you to look up information in a graph.
| The curve is rising very gradually and flattening out at a value |
| around 1.3 between cell counts of |
10.0 |
× |
108
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and |
12.0 |
× |
108
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. |
| So it will be higher than 1.3, which eliminates (A) and (B), |
| The trend of the curve, if you just continued drawing the pattern |
| with your pencil, indicates that a cell count of |
15.0 |
× |
108
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should |
| coincide with an optical density of greater than 1.3 but less than |
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