If a test conducted in a school has a high difficulty level, then most of the students will have a poor-to-average performance in it. This bulk of students will form the maximum part of the distribution, towards the left side of the positively skewed distribution curve. The highest marks in the test will be obtained only by a couple of meritorious students, which forms the right tail of extreme values. The students with very high marks will shift the mean towards the right, making it a positively skewed distribution. In other words, there will be a higher frequency of low scores and a lower frequency of high scores.
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