10/23/23

How large of a sample size is required?
You want to obtain a sample to estimate a population proportion. Based on previous evidence, you believe the population proportion is approximately p∗=78%. You would like to be 95% confident that... more
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10/23/23

Write the mixed numbers as improper fractions
write the mixed numbers as improper fractions and vice1. 41/202. 38/93. 70/134. 76/95. 2 3/56. 5 3/57. 6 1/78. 11 4/9
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10/22/23

Assume the random variable X is normally​ distributed, with mean 60 and standard deviation 5 . Find the 6th percentile.
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10/20/23

For a standard normal distribution, find: P(z > 2.14)
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10/20/23

Double the difference between a number n and 5 is 32
Double the difference between a number n and 5 is 32
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10/20/23

How to find point estimate mean and SD
The National Football League (NFL) polls fans to develop a rating for each football game (NFL website, October 24, 2012). Each game is rated on a scale from  (forgettable) to  (memorable). The fan... more
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10/19/23

Average SAT scores of first-year students?
SAT scores are normally distributed with a mean of 1,500 and a standard deviation of 300. An administrator at a college is interested in estimating the average SAT score of first-year students. If... more
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10/18/23

People with children
Out of 300 people sampled, 255 had children. Based on this, construct a 95% confidence interval for the true population proportion of people with children.  What is the 90% confidence interval to... more
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10/18/23

Average SAT scores of first-year students
SAT scores are normally distributed with a mean of 1,500 and a standard deviation of 300. An administrator at a college is interested in estimating the average SAT score of first-year students. If... more
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10/18/23

Confidence level margin of error
Assuming the population has an approximate normal distribution, if a sample size n = 12 has a sample mean x-bar = 47 with a sample standard deviation s = 6, find the margin of error at a 98%... more
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10/18/23

Mean temperature
A researcher must estimate the mean temperature (in degrees Fahrenheit) with the following sample temperatures: 44.5, 49.5, 46.9, 62.7, 64.7, 50.3. Assuming the population of temperatures are... more
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10/18/23

Population normal distribution

Assuming the population has an approximate normal distribution, if a sample size n=21 has a sample mean x-bar=37 with a sample standard deviation s=6, find the margin of error at an 80% confidence... more
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10/18/23

High temperatures in 10 small towns
The high temperatures (in degrees Fahrenheit) of a random sample of 10 small towns are 97.3, 98.4, 98.5, 96.6, 96.9, 98.9, 98, 97.6, 99, 97.2. Assume high temperatures are normally distributed.... more
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10/18/23

Confidence Interval Sample Size
We want to obtain a sample to estimate a population mean. Based on previous evidence, researchers believe the population standard deviation is approximately s=56.5. We would like to be 95%... more
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10/18/23

Based on this, construct a 95% confidence interval for the true population mean turtle weight.
You measure 41 turtles' weights, and find they have a mean weight of 70 ounces. Assume the population standard deviation is 8 ounces. Based on this, construct a 95% confidence interval for the true... more
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10/18/23

I need the answer to this please?
Determine the area under the standard normal curve that lies to the left of (a) Z=-1.67, (b) Z=-1.35, (c) Z=-1.69, and (d) Z=-0.93.
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10/18/23

The time married men with children spend on child care averages 6.5 hours per week.

You belong to a professional group on family practices that would like to do its own study to determine if the time married men in your area spend on child care per week differs from the reported... more
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10/18/23

Continuous Probability Distribution Question
The probability density of a random variable X is given in the figure below.From this density, the probability that X > 1.18 or X < 0.34 is: ___________
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10/17/23

I need an answer to this question please?
An elevator has a placard stating that the maximum capacity is 4100lb-27 passengers. So, 27 adult male passengers can have a mean weight of up to 4100/27=152 pounds. Assume that weights of males... more
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10/17/23

I don't understand where you got 1.96 in this problem
Hi,I am totally confused how to find z - which table to get it from or which formula to use in which calculator for confidence intervals. I am guessing it is confidence intervals that is being... more
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10/17/23

Use this to predict the number of situps a person who watches 12 hours of TV can do (to one decimal place)
A regression was run to determine if there is a relationship between hours of TV watched per day (x) and number of situps a person can do (y).The results of the regression... more
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10/17/23

Based on this, construct a 99% confidence interval for the true population mean watermelon weight.
You measure 21 watermelons' weights, and find they have a mean weight of 67 ounces. Assume the population standard deviation is 10.9 ounces. Based on this, construct a 99% confidence interval for... more
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10/17/23

Find the margin of error at a 90% confidence level.
In a survey, 22 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $46 and standard deviation of $9. Find the margin of... more
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10/17/23

Help with Stats
The population of weights of a particular fruit is normally distributed, with a mean of 432 grams and a standard deviation of 30 grams. If 4 fruits are picked at random, then 14% of the time,... more
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10/17/23

Wall Street Journal reported on several studies that show massage therapy has a variety of health benefits & it's not too expensive.

A sample of 10 typical 1 hr massage therapy sessions showed an average charge of $61. The population standard deviation for a one-hour session is σ = $5.6. Using 95% confidence, what is the margin... more
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