Exam 7: Sampling and Sampling Distributions

Kristen Ashford purchased the subscribers list for Wind Surfing magazine.She plans to survey a sample of the subscribers before using the list in her mail order business.The names are numbered consecutively from 1 to 5,000.Kristen chooses her sample by selecting four-digit numbers (1 to 5,000)from a random number table.Her sample is a ___.

Suppose a population has a mean of 400 and a standard deviation of 24.If a random sample of size 144 is drawn from the population, the probability of drawing a sample with a mean between 393.5 and 396.5 is ___.

A carload of steel rods has arrived at Cybermatic Construction Company.The car contains 50,000 rods.Claude Ong, Manager of Quality Assurance, directs his crew to measure the lengths of 100 randomly selected rods.If the population of rods has a mean length of 120 centimetres and a standard deviation of 0.05 centimetres, the probability that Claude's sample has a mean between 119.985 and 120.0125 centimetres is ___.

If the population proportion is 0.90 and a sample of size 64 is taken, what is the probability that the sample proportion is less than 0.88?

A carload of steel rods has arrived at Cybermatic Construction Company.The car contains 50,000 rods.Claude Ong, Manager of Quality Assurance, directs his crew to measure the lengths of 100 randomly selected rods.If the population of rods have a mean length of 120 centimetres and a standard deviation of 0.05 centimetres, the probability that Claude's sample has a mean less than 119.985 centimetres is ___.

Albert Abbasi, VP of Operations at Ingleside International Bank, is evaluating the service level provided to walk-in customers.Accordingly, he plans a sample of waiting times for walk-in customers.If the population of waiting times has a mean of 15 minutes and a standard deviation of 4 minutes, the probability that Albert's sample of 64 will have a mean less than 16 minutes is ___.

On Saturdays, cars arrive at David Zebda's Scrub and Shine Car Wash at the rate of 80 cars per hour during the ten-hour shift.David wants a sample of 40 Saturday customers to answer the long version of his quality service questionnaire.He randomly selects 9 as a starting point and instructs the crew to select the 9th customer and every 20^th customer thereafter (9, 29, 49, etc.).His sample is a ___.

A carload of various palletized aluminum castings has arrived at Mansfield Motor Manufacturers.The car contains 1,000 pallets of 100 castings each.Mario Munoz, Manager of Quality Assurance, directs the receiving crew to deliver the 127th and 869th pallets to his crew for 100% inspection.Mario randomly selected 127 and 869 from a table of random numbers.Mario's sample of 200 castings is a ___.

Catherine Chao, Director of Marketing Research, needs a sample of Ottawa households to participate in the testing of a new toothpaste package.If 40% of the households in Ottawa prefer the new package, the probability that Catherine's random sample of 300 households will have a sample proportion between 0.35 and 0.45 is ___.

Pinky Bauer, Chief Financial Officer of Harrison Haulers, Inc., suspects irregularities in the payroll system.She knows that 2,500 payroll vouchers have been issued since January 1, 2000, and her staff doesn't have time to inspect each voucher.So, she randomly selects 53 as a starting point and orders her staff to inspect the 53rd voucher and each voucher at an increment of 100 (53, 153, 253, etc.).Her sample is a ___.

Kristen Ashford purchased the subscribers list for Wind Surfing magazine.She plans to survey a sample of the subscribers before using the list in her mail order business.She randomly selects the fourth name as a starting point and then selects every 50th subsequent name (54, 104, 154, etc.).Her sample is a ___.

Catherine Chao, Director of Marketing Research, needs a sample of households to participate in the testing of a new toothpaste package.She directs the seven members of her staff to find five households each.Catherine's sample is a ___.

A population list, map, directory, or other source used to represent the population from which a sample is taken is called the census.

In an instant lottery, your chance of winning is 10.0%.If you play the lottery 100 times and the outcomes are independent, the probability that you win at least 15.0% of the time is ______.

According to the central limit theorem, if a sample of size 100 is drawn from a population with a mean of 80, the mean of all sample means would equal ___.

Suppose the population of all public Universities shows the annual parking fee per student is normally distributed with a mean of $110 with a standard deviation of $18.If a random sample of size 49 is drawn from the population, the probability of drawing a sample with a sample mean between $112 and $115 is closest to _______.

Increasing the sample size causes the numerical value of the standard error of the mean to increase.

According to the central limit theorem, if a sample of size 64 is drawn from a population with a mean of 56, the mean of all sample means would equal ___.

A carload of steel rods has arrived at Cybermatic Construction Company.The car contains 50,000 rods.Claude Ong, Manager of Quality Assurance, directs his crew to measure the lengths of 100 randomly selected rods.If the population of rods has a mean length of 120 centimetres and a standard deviation of 0.05 centimetres, the probability that Claude's sample has a mean greater than 120.0125 centimetres is ___.

Sampling errors cannot by determined objectively for nonrandom sampling techniques.