Sampling distribution

Sampling distribution - STAT 1220-090 HOMEWORK 4 Name: _...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
STAT 1220-090 HOMEWORK 4 Fall 2011 Name: ____________ Score_________ 1. Given that the population mean μ = 68 and population standard deviation σ = 12, find the sample mean μX and the sample standard deviation σX for a random sample of size 50 (round off to two decimal places.) (a) 68, 12 (b) 9.62, 12 (c) 9.62, 1.70 (d) 68, 1.70 (e) 68, .24 For questions 2 and 3. It is known that the mean diameter of pine trees in a national forest is 9.6 (inches) with a standard deviation 2.4 (inches). Assuming that the tree diameters are distributed normally. 2. If a pine tree is to be selected randomly from this forest, what is the probability that its diameter will fall between 7.2 inches and 14.4 inches? (a) .1359 (b) .6826 (c) .9544 (d) .8185 (e) .9772 3. If a selected pine tree from this forest is at the 90th percentile, what is its diameter (rounded off to two decimal places) in inches? (a) 12.67 (b) 14.30 (c) 13.55 (d) 14.69 (e) 18.19 4. Personal best finishing times for a particular race in high school track meets are normally distributed with mean 5.27 minutes and standard deviation .42 minutes. If the qualifying time for this event for the regional championship is to be set so that only four percent of all runners
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 3

Sampling distribution - STAT 1220-090 HOMEWORK 4 Name: _...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online