FORESTRY
AGRICULTURAL STATISTICS AND ECONOMICS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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When n < 30
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When n ≥ 30
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When all of the planets align
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When Ms. O said to
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Detailed explanation-1: -A. A z-test is used to test a Null Hypothesis if the population variance is known, or if the sample size is larger than 30, for an unknown population variance. A t-test is used when the sample size is less than 30 and the population variance is unknown.
Detailed explanation-2: -The t-distribution gives more probability to observations in the tails of the distribution than the standard normal distribution (a.k.a. the z-distribution).
Detailed explanation-3: -The parametric test called t-test is useful for testing those samples whose size is less than 30. The reason behind this is that if the size of the sample is more than 30, then the distribution of the t-test and the normal distribution will not be distinguishable.