For a sample of 20 IQ scores the mean score is 105.8. The standard deviation, $\sigma _ { , }$ is 15. Determine whether a normal distribution or a t-distribution should be used or whether neither of these can be used to construct a
Confidence interval. Assume that IQ scores are normally distributed.
A)Use normal distribution.
B)Use the t-distribution.
C)Cannot use normal distribution or t-distribution.

Question

Quizplus · Accepted Answer

Since the population standard deviation is known and the sample size is 20, which is less than 30, the normal distribution can be used because the IQ scores are assumed to be normally distributed.

For a Sample of 20 IQ Scores the Mean Score σ,\sigma _ { , }σ,​

For a Sample of 20 IQ Scores the Mean Score $\sigma _ { , }$