STTN115 - Descriptive Statistics and Inference - QUIZ
STTN115 · Descriptive Statistics and Inference
North-West University
Questions
10 Questions
Practice 10 questions on STTN115 - Descriptive Statistics and Inference at North-West University. Free AI-generated quiz on uNotes — track your score, retake anytime.
1Given that X is a continuous random variable with probability density function f(x), what is the value of the total area under the probability density curve?
2In a standard normal distribution, if P(Z ≥ 1.5) = 0.0668, what is the value of P(Z ≤ -1.5) based on the property of symmetry?
3Using the provided standard normal table, determine the value of P(Z < 1.05).
4If sample A has a larger standard deviation than sample B, but both have the same sample size, which sample will produce a wider 95% confidence interval for the population mean?
5Based on the annual battery sales data for the years 1990 to 1994 (44, 50, 51, 46, 47), calculate the five-year moving average for the year 1992.
6A sock length follows a normal distribution with mean 20 cm and standard deviation 10.5 cm. Calculate the Z-score for a sock that is 25 cm long (round to two decimal places).
7For a t-distribution with 15 degrees of freedom (df = 15), find the value of k such that P(T > k) = 0.10 using the provided t-table.
8In a market research study of 500 adults, 421 owned cell phones. Calculate the point estimator (sample proportion) for the proportion of adults who own cell phones.
9If a calculated 95% confidence interval for the mean height of a population is [168.804, 181.196], does this interval support the hypothesis that the true population mean is 183 cm? (Answer Yes or No)
10In the zero-sum method for calculating a long-term trend line (y = a + bx), if the sum of xy is 80 and the sum of x squared is 110, what is the slope b of the trend line (round to three decimal places)?
