Statistics MCQs
Topic Notes: Statistics
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
1
Given a sample size of 92 drawn from an infinite population, what can be concluded about the sampling distribution of the sample mean?
Answer:
Normal because of the central limit theorem
The Central Limit Theorem states that for a sufficiently large sample size (typically n ≥ 30), the sampling distribution of the sample mean will be approximately normally distributed, regardless of the shape of the underlying population distribution. With a sample size of 92, this condition is well-satisfied.
2
For a random sample of size 17 from a population of 200 with a mean of 36 and standard deviation of 8, what describes the sampling distribution of the sample mean?
Answer:
None of these alternatives is correct
With a sample size of 17, which is less than 30, the Central Limit Theorem does not apply unless the population is known to be normal. Since the problem does not state that the population is normally distributed, we cannot conclude that the sampling distribution is approximately normal.
3
As the number of trials 'n' increases significantly, which distribution does the binomial distribution approach?
Answer:
Normal dist
According to the De Moivre-Laplace theorem, a specific case of the Central Limit Theorem, the binomial distribution converges to a normal distribution as the number of trials 'n' becomes large, provided that the probability of success 'p' is not extremely close to 0 or 1. This approximation allows for easier calculation of probabilities using the normal curve.
4
Given a sample of 24 observations from a population of 150, what is the nature of the sampling distribution of the mean?
Answer:
Normal if the population is normally distributed
The Central Limit Theorem generally requires a sample size of at least 30 to assume normality of the sampling distribution of the mean regardless of the population shape. With a sample size of 24, we cannot rely on the CLT; therefore, the sampling distribution is only normal if the underlying population is normally distributed.
5
Which statistical theorem states that the sampling distribution of the sample mean approaches a normal distribution as the sample size increases, regardless of the population's distribution?
Answer:
central limit theorem
The Central Limit Theorem (CLT) is a fundamental principle in statistics. It asserts that for a sufficiently large sample size, the distribution of the sample means will be approximately normal, even if the underlying population distribution is not normal. This theorem is essential for performing inferential statistical tests.
6
Under what condition is the normal distribution most commonly applied in statistical inference?
Answer:
n is large
The normal distribution is widely used in inferential statistics when the sample size (n) is large. According to the Central Limit Theorem, as the sample size increases, the distribution of the sample mean tends toward normality, even if the population itself is not normally distributed. This property allows researchers to perform hypothesis tests and construct confidence intervals with greater reliability.
7
According to the Central Limit Theorem, what is the shape of the sampling distribution of the sample mean for large sample sizes?
Answer:
Always normal for large sample sizes
The Central Limit Theorem asserts that as the sample size increases, the sampling distribution of the sample mean tends toward a normal distribution, even if the population from which the samples are drawn is not normally distributed. This is a cornerstone of inferential statistics, allowing for hypothesis testing and confidence interval construction.
8
As the sample size increases, the sampling distribution of the sample mean tends toward which type of distribution?
Answer:
Large
The question refers to the Central Limit Theorem, which states that as the sample size increases, the sampling distribution of the sample mean approaches a normal distribution regardless of the shape of the underlying population distribution. While the terminology 'Large' is used here to describe the distribution's behavior in the limit, it fundamentally points to the asymptotic normality of the sample mean.
9
In the context of statistical hypothesis testing, what is the conventional threshold for a sample size to be considered 'large'?
Answer:
n > or = 30
In statistics, a sample size of n = 30 is widely accepted as the threshold for a large sample. This convention is significant because, according to the Central Limit Theorem, the sampling distribution of the sample mean approaches a normal distribution as the sample size increases, regardless of the population distribution. Once the sample size reaches 30, the normal approximation is generally considered sufficiently accurate for performing Z-tests.