class intervals

A sample of 10 mathematics books of grade 7 had the following number of pages. Find the 98% confident interval for the variance of the pages. Assume that the variable is normally distributed. 1000 1320 590 820 1150 1570 1090 1585 995 1285 => between 38110 and 345769 or between 49895 and 5..

From the stem-and-leaf plot, find how many data values are less than 93, from the intervals 80 - 89, 90 - 99, 100 - 109, and 110 - 119. => 6 or 3 or 4 or 5..

Based on the stem-and-leaf plot, how many data items are there in the intervals 20 - 29, 30 - 39, 40- 49, 50- 59 and 60 - 69? => 17 or 19 or 23 or 22..

From the stem-and-leaf plot, find how many data values are less than 100, from the intervals 80 - 89, 90 - 99, 100 - 109 and 110 - 119. => 8 or 9 or 6 or 7..

A recent study of 50 people in a city found that 70% of the people have less than average incomes for the city. How many people should be surveyed to estimate the true proportion of people having an income of less than average with a 99% confidence interval 4% wide? => 874 or 375 or 65 or..

Suppose that for the past 15 years the variance for the number of skydivers met with accident each year has been 16. Find the 90% confidence interval for the true variance. Assume that the variable is normally distributed. => between 9 and 31 or between 11 and 39 or between 10 and 34 or b..

When should the t distribution be used to find a confidence interval for the mean? => When the sample size of population is greater than 30 and the standard deviation is known. or When the sample size of population is less than 30 and the standard deviation is known. or When the sample si..

The number of ATM transactions of a bank per day were recorded at 12 locations in a city. The mean of the sample was 88.5 transactions, with a sample standard deviation of 42. Find the 98% confidence interval of the true mean. => 19.06 < μ < 157.94 or 78.99 < μ < 98.01 o..

A sample of scores of 250 candidates has a mean of 47.2 with a standard deviation of 18.6. Find 90% and 95% confidence interval of the population mean and determine which is larger? => (45.3, 49.1) and (44.9, 49.5) and 95% or (45.26, 49.14) and (44.89, 49.51) and 90% or (44.89, 49.51) and..

A random sample of 81 students was tested for the problem solving approach skills. The variance of the scores obtained from the sample was found to be 144. Find the 80% confidence interval for the variance and standard deviation. Assume that the variable is normally distributed. => 122 &l..