Exam 7: Sampling Distributions

A study at a college in the west coast reveals that,historically,45% of the students are minority students.If random samples of size 75 are selected,the standard error of the proportion of students in the samples who are minority students is .

The amount of time it takes to complete an examination has a left skewed distribution with a mean of 65 minutes and a standard deviation of 8 minutes.If 64 students were randomly sampled,the probability that the sample mean of the sampled students exceeds 71 minutes is approximately 0.

The standard error of the sampling distribution of a sample proportion is where p is the sample proportion.

The amount of tea leaves in a can from a production line is normally distributed with μ = 110 grams and σ = 25 grams.A sample of 25 cans is to be selected.So,95% of all sample means will be greater than how many grams?

The sample proportion is an unbiased estimate of the population proportion.

If the population distribution is symmetric,the sampling distribution of the mean can be approximated by the normal distribution if the samples contain 15 observations.

The amount of tea leaves in a can from a production line is normally distributed with μ = 110 grams and σ = 25 grams.A sample of 25 cans is to be selected.What is the probability that the sample mean will be less than 100 grams?

SCENARIO 7-5 According to an article,19% of the entire population in a developing country has high-speed access to the Internet.Random samples of size 200 are selected from the country's population. -Referring to Scenario 7-5,among all the random samples of size 200,_____% will have between 9% and 29% who have high-speed access to the Internet.

SCENARIO 7-1 The time spent studying by students in the week before final exams follows a normal distribution with a standard deviation of 8 hours.A random sample of 4 students was taken to estimate the mean study time for the population of all students. -Referring to Scenario 7-1,what is the probability that the sample mean is more than 3 hours below the population mean?

SCENARIO 7-5 According to an article,19% of the entire population in a developing country has high-speed access to the Internet.Random samples of size 200 are selected from the country's population. -Referring to Scenario 7-5,among all the random samples of size 200,_____% will have between 14% and 24% who have high-speed access to the Internet.

For sample sizes greater than 30,the sampling distribution of the mean will be approximately normally distributed

The amount of bleach a machine pours into bottles has a mean of 36 oz.with a standard deviation of 0.15 oz.Suppose we take a random sample of 36 bottles filled by this machine.The probability that the mean of the sample exceeds 36.01 oz.is .

Suppose ? = 50 and $\sigma$ = 10 for a population.In a sample where n = 100 is randomly taken,90% of all possible sample means will fall between 49 and 51.

The amount of bleach a machine pours into bottles has a mean of 36 oz.with a standard deviation of 0.15 oz.Suppose we take a random sample of 36 bottles filled by this machine.The sampling distribution of the sample mean has a mean of 36 oz.

The amount of bleach a machine pours into bottles has a mean of 36 oz.with a standard deviation of 0.15 oz.Suppose we take a random sample of 36 bottles filled by this machine.The probability that the mean of the sample is less than 36.03 is .

SCENARIO 7-3 The lifetimes of a certain brand of light bulbs are known to be normally distributed with a mean of 1,600 hours and a standard deviation of 400 hours.A random sample of 64 of these light bulbs is taken. -Referring to Scenario 7-3,what is the probability that the sample mean lifetime is more than 1,550 hours?

The standard error of the population proportion will become larger

The amount of tea leaves in a can from a production line is normally distributed with μ = 110 grams and σ = 25 grams.A sample of 25 cans is to be selected.What is the probability that the sample mean will be between 100 and 120 grams?

If the amount of gasoline purchased per car at a large service station has a population mean of 15 gallons and a population standard deviation of 4 gallons and a random sample of 4 cars is selected,there is approximately a 68.26% chance that the sample mean will be between 13 and 17 gallons.

A manufacturer of power tools claims that the mean amount of time required to assemble their top-of-the-line table saw is 80 minutes with a standard deviation of 40 minutes.Suppose a random sample of 64 purchasers of this table saw is taken.So,the middle 95% of the sample means based on samples of size 64 will be between_____ and _____.