random samples

The average price for different configurations of laptops in a shop is $1,300. Assume the standard deviation is $300. If a random sample of 9 laptops is selected, then find the probability that the mean of the sample will be less than $1,000. => 0.13% or 49.87% or 99.8..

Average score of the students in a statistics contest is 65, and the standard deviation is 15. If a random sample of 16 students who participated in the contest are selected, then find the probability that the sample mean of the scores lies between 61 and 67. => 15.52%..

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 di..

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 standard error. => 6...

The 95% confidence interval for the mean number of tablets in a bottle of calcium tablets is between 149.04 and 150.96. The standard deviation is 3 tablets. Find the size of the random sample that was used to determine this interval. => 40 or 38 or 6 or 150..

The 95% confidence interval for the mean weight of a sack of potatoes is between 4.92 and 5.08. If a random sample of 32 sacks was used to determine this interval, what was the standard deviation? => 0.04 or 0.16 or 3.92 or 0.23..

The percentage of Americans of 25 years and above having at least some college education is 50.9. What is the probability that in a random sample of 400 Americans in this age group, only less than 220 will have at least some college education? => 44.41% or 5.95% or 9.55% or 94.4..

The probability that a student has access to Internet from his/her home is 40%. If a random sample of 100 students is selected, then find the probability that between 50% and 60% of the students have access to Internet from their home. => 2.61% or 0.026% or 97.39% or 26.1%..

In a school, 600 out of 1,000 students support team A. If a random sample of 100 students is selected, then what is the probability that the proportion of students who support team A lies between 0.5 and 0.7? => 48.38% or 96.76% or 99.76% or 3.24%..

Jail inmates can be classified into one of four crime categories. Suppose a random sample of 1000 female inmates and a random sample of 1000 male inmates were taken. Each inmate was classified into a crime category. The results are tabulated as shown. At &alp..