Question

As the sample size INCREASES for computing a confidence interval, the width of the confidence interval DECREASES. 12 When the population standard deviation sigma is assumed known, a confidence interval can assume NORMALITY of the SAMPLE MEAN if the sample size is greater than 30. 12 A SYMMETRIC histogram implies the plotted variable is NORMALLY distributed. 12 The goal when using confidence intervals is to have WIDE INTERVALS to be assured that the interval contains the population parameter. 12 A NORMAL distribution will have an approximately SYMMETRIC histogram. 12 A Z-SCORE can be interpreted for a value as the value's number of standard deviation above or below the mean. 12 A CONFIDENCE INTERVAL can be interpreted as the single best ESTIMATE of a population parameter. 12 As the STANDARD DEVIATION decreases for a normal distribution, the values become LESS concentrated around the MEAN. 12 INCREASING the confidence level of a confidence interval from 90% to 99% makes the interval SHORTER. 12 For a PROBABILITY DENSITY FUNCTION, the area between two values aand b is the probability a randomly selected individual will have a value between aand b.

1. TRUE 2. FALSE

Answer 1

Ans:

(True)As the sample size INCREASES for computing a confidence interval, the width of the confidence interval DECREASES.

(True)When the population standard deviation sigma is assumed known, a confidence interval can assume NORMALITY of the SAMPLE MEAN if the sample size is greater than 30.

(False)If the graph is approximately bell-shaped and symmetric about the mean, you can usually assume normality.

(False),we increase the confidence level to have wider interval,but it increases only the confidence level and does not make sure that it will include the parameter.

(True)A NORMAL distribution will have an approximately SYMMETRIC histogram.

(True) A z score of 2 means that raw score is 2 standard deviations above the mean.

(False) Confidence interval gives a range of values,not a single value.

(False) As the standard deviation increases,spread of the values around the mean decreases and values are more concentrated around the mean.

(False) Increasing the confidence level,confidence interval becomes more wider.

(True) For a pdf, the area between two values a and b is the probability a randomly selected individual will have a value between aand b.