class intervals

The standard deviation of the hemoglobin values (g/100ml) of 10 children is 1.7. Find the 99% confidence interval for the variance and standard deviation. Assume that the variable is normally distributed. => 1.26 < σ 2 < 14.75 ; 1.12 < σ < 3.84 or 1.1 < σ ..

A survey of 2,000 people in a city found 72% of them take bread and butter as their breakfast. Find the 90% confidence interval of the true proportion of people taking bread and butter as their breakfast. => 71% < p < 73% or 71.2% < p < 72.8% or 28% < p < 72% or 70.35% &..

Based on a sample of 150 U.S couples, it was found that in 108 couples the children are taller than the couples. Find the 95% confidence interval for the proportion of all U.S couples where children are taller than the parents. => 68.3% < p < 75.7% or 64.8% < p < 79.2% or 20.8..

A teacher wishes to estimate the average weight of 10 students of grade 6 taken randomly. The weight(in pounds) of the students are shown. Find the 99% confidence interval for the variance for the weights of students. Assume that the variable is normally distributed. 90 88 96 85 91 93 82 ..

95% confidence interval of a population mean(μ) with a sample size of 60 was found out as 14.5 < μ < 17.6. Another study calculated the 95% confidence interval as 14.3 < μ < 17.8. Which among the following can be the possible sample size of the second study?..

A random sample of 52 days taken at a chemical laboratory shows that an average of 36 specimens were tested per day. The standard deviation of the population is 6. I. Find the 99% confidence interval of the mean number of specimens tested each day at the laboratory. II. Find the 99% confi..

The life expectancy (years) at birth of a random sample of 20 countries is shown here. Find the 99% confidence interval for the standard deviation. Assume that the variable is normally distributed. 77 67 76 69 60 57 59 55 57 53 54 50 51 49 50 49 72 69 50 48 => between 6.65 and 15.42 or be..

The average annual expenditure per consumer unit for health care and the per-capita income for a period of 5 years is shown. Find the 99% prediction interval for the per-capita income if the health care cost is $2000. Health care cost (in $1000) 1.6 1.7 1.8 1.9 1.9 Per-capita income (in $..

A standard notebook is supposed to have on an average, 200 pages, with a standard deviation of 2 pages. From a supply of 2500 notebooks, a random sample of 40 notebooks was taken and found that the mean number of pages in the notebook was 197. Determine the 95% confidence interval. => The..

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 ? => 19 or 17 or 23 or 22..