Question

A sample of 100 obese adults from a population following a normal distribution was put on a low carbohydrate diet. For this sample, the average weight loss was 10 lb and the standard deviation was 4 lb. Find a 90% confidence interval for the variance of the population.

Answer #1

Solution :

n = 100

df = n - 1 = 99

x̄ = average weight loss = 10 lb

s = standard deviation = 4 lb

CI =confidence interval = 90%

Using Chi square Distribution, excel commands

Lower critical value = CHIINV(0.05,99) = 77.046

Upper Critical Value = CHIINV(0.95,99) = 123.225

Upper Limit = ((n-1)*s*s)/Lower critical value = (99*4*4)/77.046 = 20.5591

Lower Limit = ((n-1)*s*s)/Upper critical value = (99*4*4)/123.225 = 12.8545

The 90% confidence interval for population variance,

**(12.8545 , 20.5591)**

An advertisement for a diet program described a study performed
on 70 obese adults. Each person in the study was weighed before
beginning the diet and then 5 weeks after starting the diet. The
difference was recordeddasha positive value indicates a person lost
weight on the diet while a negative value indicates the person
gained weight while on the diet. The advertisement gave a 95%
confidence interval for the average weight change while on the
diet: (minus1,5) lbs. The advertisement...

Q.1. ) Low-carbohydrate diet A study plans to have a sample of
obese adults follow a proposed low-carbohydrate diet for three
months. The diet imposes limited eating of starches (such as bread
and pasta) and sweets, but otherwise no limit on calorie intake.
Consider the hypothesis, The population mean of the values of
weight change (= weight at start of study - weight at end of study)
is a positive number.
• a. Is this a null or an alternative...

3. In a test of weight loss programs, 40 adults used the Atkins
weight loss program. After 12 months, their mean weight loss was
found to be 2.1 lb, with a standard deviation of 4.8 lb. Construct
a 90% confidence interval estimate of the standard deviation of the
weight loss for all such subjects. Does the confidence interval
give us information about the effectiveness of the diet?

A simple random sample from a population with a normal
distribution of 100 body temperatures has
x overbar =9 8.40°F ands = 0.62°F.
Construct a 98% confidence interval estimate of the standard
deviation of body temperature of all healthy humans. Is it safe to
conclude that the population standard deviation is less than
2.10°F?
___°F < σ < ___°F
(Round to two decimal places as needed.)
Is it safe to conclude that the population standard deviation is
less than 2.10°F?...

In the following situation, assume the random variable is
normally distributed and use a normal distribution or a
t-distribution to construct a 90% confidence interval for the
population mean. If convenient, use technology to construct the
confidence interval.
(a) In a random sample of 10 adults from a nearby county, the
mean waste generated per person per day was 3.57 pounds and the
standard deviation was 1.95 pounds.
(b) Repeat part (a), assuming the same statistics came from a
sample...

A simple random sample from a population with a normal
distribution of 100 body temperatures has x=98.90 degrees Upper F°F
and s=0.63 degrees Upper F°F. Construct an 95% confidence interval
estimate of the standard deviation of body temperature of all
healthy humans.

Using the simple random sample of weights of women from a data
set, we obtain these sample statistics: nequals40 and x
overbarequals153.03 lb. Research from other sources suggests that
the population of weights of women has a standard deviation given
by sigmaequals30.91 lb. a. Find the best point estimate of the mean
weight of all women. b. Find a 90% confidence interval estimate of
the mean weight of all women. Click here to view a t distribution
table. LOADING... Click...

(1 pt) A random sample of 100 observations produced a mean of
x-bar = 23.1 from a population with a normal distribution and a
standard deviation = 2.42. (a) Find a 90% confidence interval (b)
Find a 99% confidence interval (c) Find a 95% confidence
interval

Are low-fat diets or low-carb diets more effective for weight
loss? A sample of 70 subjects went on a low-carbohydrate diet for
six months. At the end of that time, the sample mean weight loss
was 10.5 pounds with a sample standard deviation of 7.09 pounds. A
second sample of 76 subjects went on a low-fat diet. Their sample
mean weight loss was 18.0 with a standard deviation of 7.26. Can
you conclude that their was no difference in the...

A simple random sample from a population with a normal
distribution of 105 body temperatures has x =98.1°F and s=0.61°F.
Construct a 90%
confidence interval estimate of the standard deviation of body
temperature of all healthy humans.

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 10 minutes ago

asked 20 minutes ago

asked 34 minutes ago

asked 42 minutes ago

asked 42 minutes ago

asked 49 minutes ago

asked 53 minutes ago

asked 53 minutes ago

asked 54 minutes ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago