The coal mining technique where layers of mountains are removed from the top down and the resulting spoils are placed in adjacent valleys is known as mountaintop removal mining.
Mountaintop removal mining uses a scale machinery technique that removes the topmost layer of the mountain. It helps us to access coal used for daily human uses. The coal is extracted from the mountain layers from each layer.
The layer of the mountain consists of rock, soil, minerals, and other materials which contain a bulk in structure. A large number of coal is typically deposited in valleys. The minerals and other materials are removed from the natural practices.
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A representative sample is one that accurately reflects a larger a) control group. b) population. c) correlation coefficient. d) dependent variable.
A representative sample is one that accurately reflects a larger population. Thus, option B is the correct choice.
A representative sample is a group or set of subjects chosen from a bigger population, with characteristics or features that resemble the population. These similarities may be observed or measured for any given feature, which includes age, gender, race, education, income level, job status, and other features. Representativeness is a crucial aspect of statistical inferences, which allow researchers to generalize results from a sample to a population.
In other words, a representative sample is a subset of a population that accurately represents the population as a whole. The goal of a representative sample is to capture the essential characteristics of the population in question so that the sample can be used to make inferences about the larger population.
Sample vs PopulationA population is defined as a group of individuals, objects, or measurements that are being studied. A sample is defined as a smaller group that is drawn from the population to represent it. A sample may or may not accurately reflect the characteristics of the larger population. A representative sample is one that accurately reflects a larger population.
Hence, option B- population is the correct answer.
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3 of 12 Telescopes used for research do not use eyepieces. Why not? Eyepieces are not needed once the primary mirror lens becomes sufficiently large. Eyepieces are too far above the ground to reach with large telescopes. CCD detectors (sensors) are superior to the human eye for collecting photons. Large telescopes do not have sufficiently high resolving power to benefit from using an eyepiece 4 of 12 How much of a radioactive element remains after a time of 3 half-lives? 1/16 1/8 1/4 1/2 None of the above, because it depends on the specific element.
Telescopes that are used for research purposes do not always use eyepieces. CCD detectors (sensors) are better at collecting photons than the human eye. CCD sensors are therefore used in place of the eyepiece in some telescopes. Therefore option (A) is correct answer and 18 radioactive element.
Since CCD sensors detect light more accurately and precisely than the human eye, they are frequently used instead of eyepieces. The correct answer is: CCD detectors (sensors) are superior to the human eye for collecting photons.
The amount of radioactive material that remains after a certain period of time can be calculated using the formula:
Amount = initial amount × (1/2) /(number of half-lives)
The amount of a radioactive element that remains after 3 half-lives can be calculated by substituting 3 for the number of half-lives. So, the answer to the question is:
1/8 (which is 1/2 × 1/2 × 1/2 = 1/8)
Therefore, the answer is: 1/8.
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