sample want ads

Hannah wants to find out the amount of time spent by her school students watching TV. Choose the sampling method that she should take on. => ask her class students or ask her colleagues or randomly select a few grades, and ask few students in each grade or ask her children..

A university dean wishes to estimate within $200 the true amount of money spent on administration of its colleges by the University each year. If he wants to be 95% confident, how large a sample is necessary? The standard deviation is known to be $1200. => 600 or 1176 or 139 or ..

The average intake of added sugars by a person is observed to be 68 gm/day for 10 days with a sample standard deviation of 2.86 grams. Find the 99% confidence interval of the true mean. => 65.1 < μ < 70.9 or 64 < μ < 01 or 67 < μ < 69 or 65 < μ &..

A researcher wishes to estimate the average daily wage (industrial composite) of industrial workers. A previous study showed that the standard deviation is $23. How large a sample must be selected if he wants to be 99% confident of getting an interval that contains the true mean..

A management firm wants to estimate the mean cost of repairing the apartments that are vacated by tenants. A sample of 18 vacated apartments resulted in a mean repair cost of $109 with a standard deviation of $12. Find the 90% confidence interval to estimate the mean repair cost..

An automobile parts supplier wants to know how long car owners plan to keep their cars with them. A random sample of 20 car owners results in a standard deviation of 3.7 years. Find a 95% confidence interval for the variance and standard deviation. Assume that the variable is no..

Brian wants to mail a packet. He packed it in a rectangular box as shown, which just meets the postal regulations. According to the postal regulations the combined length and girth of the package should not exceed 72 cm. If the length( l ) of the box is 28 cm, then what is the width of th..

A library authority wanted to find out, ahead of its bulk purchase of books, about library user's preference for the type of books. Towards this, they conducted a random sample survey among males and females and the data is presented in the table: Romance Biographies and Self-he..

The following tests of any sample confirm the presence of ammonia. The ammoniacal smell of ammonia is easily detectable having a characteristic pungent smell. Ammonia turns moist red litmus blue, and moist turmeric paper brown. When added to a solution of copper sulphat..

The antibody, which is specific to the antigen to be detected must be present in the kit. The sample, which is suspected to contain the antigen is immobilised on the ELISA plate. The specific anti body is added and allowed to react with the antigen. Washing will remove all free..