SOLUTION: a sample of the reading scores of 29 fifth gtaders has a mean of x(with the bar on top of the x)=83 and a population standard deviation of r=10.5.
a. Find 99% confidence inter
Algebra.Com
Question 281474: a sample of the reading scores of 29 fifth gtaders has a mean of x(with the bar on top of the x)=83 and a population standard deviation of r=10.5.
a. Find 99% confidence interval for the population mean scores of all fifth graders on this test.
b. How big should the sample size be for the margin of error to be no larger that 3.5?
c. 99% confidence interval if the sample was 29 fifth graders and you were given the sample standard deviation s=10.5 instead of the population standard deviation?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
a sample of the reading scores of 29 fifth gtaders has a mean of x(with the bar on top of the x)=83 and a population standard deviation of r=10.5.
a. Find 99% confidence interval for the population mean scores of all fifth graders on this test.
---
xbar = 83 ; s = 10.5, so s-hat = 10.5/sqrt(29) = 1.9498
invT(0.995,with df=28) = 2.7633
So, standard error for the population means = 2.7633*
---
95% CI: 83-2.7633 < u < 83+2.7633
95% CI: 80.2367 < u < 85.7633
=========================================
b. How big should the sample size be for the margin of error to be no larger that 3.5?
n = [1.96*10.5/3.5]^2 = 34.57
Rounding up: n = 35
==============================
c. 99% confidence interval if the sample was 29 fifth graders and you were given the sample standard deviation s=10.5 instead of the population standard deviation?
RELATED QUESTIONS
The reading test scores for the population of fifth graders is normally distributed with (answered by Shin123)
The reading test scores for the population is fifth graders is normally distributed with... (answered by ewatrrr)
Suppose x has a distribution with mean=29 and SD= 28
a) if a random sample of size n= 32 (answered by ewatrrr)
A population of values has a normal distribution with μ=17.9 and σ=94.8. You... (answered by Edwin McCravy)
Let "x bar" be the sample mean for a random sample of 12 observations from a uniform... (answered by robertb)
The reading test scores for the population of fifth graders is normally distributed with... (answered by Theo,ikleyn)
If you solve the question below, I'll be appreciated.
The scores of students on the... (answered by Theo)
On a standardized test of mathematical ability, Kim scored a 40, and John scored a 20.60. (answered by stanbon)
A population of values has a normal distribution with
u = 86.4 and σ = 83.3. You... (answered by robertb)