# Homework 4normal curve and z scores (70 pts possible)this homework

HOMEWORK 4
NORMAL CURVE AND Z SCORES (70 PTS POSSIBLE)

This homework requires both your text and your calculator. The objective of your fourth homework assignment involves answering questions related to the normal and standard normal curves.  Excel will not be a part of the assignment this week. Instead, you will submit this assignment as a Word document. You will need to use the “Normal Curve Table” in Table A-1 of the Appendix of your text that is gone over in detail (with examples) in Chapter 3.  First, be sure you view the PointeCast presentation for this week, found in the Course Content under Module 4.  This presentation provides information and goes through the steps you will need to be familiar with in order to complete this assignment. The standard normal curve is provided here to the right for your reference. Be sure to show your work in each problem.

1.    Reading readiness of preschoolers from an impoverished neighborhood (n = 20) was measured using a standardized test.  Nationally, the mean on this test for preschoolers is 30.9, with SD = 2.08.

a.    Children below the 30th percentile (in the bottom 30%) are in need of special assistance prior to attending school.  What raw score marks the cut-off score for these children?  (8 pts)

b.    What percentage of children score between 25 and 28.5? (8 pts)

c.    How many children would we expect to find with scores between 28         and 31.5?  (8 pts)

d.    Children in the top 25% are considered accelerated readers and qualify for different placement in school.  What raw score would mark the cutoff for such placement?  (11 pts)

2..    Age at onset of dementia was determined for a sample of adults between the ages of 60 and 75.  For 15 subjects, the results were  ΣX = 1008, and  Σ(X-M)2 = 140.4.  Use this information to answer the following:

a.    What is the mean and SD for this data? (8 pts)

b.    Based on the data you have and the Normal Curve Tables, what percentage of people might start to show signs of dementia at or before age 62? (8 pts)

c.    If we consider the normal range of onset in this population to be +/-1 z-score from the mean, what two ages correspond to this? (8 pts)

d.    A neuropsychologist is interested only in studying the most deviant portion of this population, that is, those individuals who fall within the top 10% and the bottom 10% of the distribution. She must determine the ages that mark these boundaries. What are these ages? (11 pts)

## Calculate the price of your order

550 words
We'll send you the first draft for approval by September 11, 2018 at 10:52 AM
Total price:
\$26
The price is based on these factors:
Number of pages
Urgency
Basic features
• Free title page and bibliography
• Unlimited revisions
• Plagiarism-free guarantee
• Money-back guarantee
On-demand options
• Writer’s samples
• Part-by-part delivery
• Overnight delivery
• Copies of used sources
Paper format
• 275 words per page
• 12 pt Arial/Times New Roman
• Double line spacing
• Any citation style (APA, MLA, Chicago/Turabian, Harvard)

# Our guarantees

Delivering a high-quality product at a reasonable price is not enough anymore.
That’s why we have developed 5 beneficial guarantees that will make your experience with our service enjoyable, easy, and safe.

### Money-back guarantee

You have to be 100% sure of the quality of your product to give a money-back guarantee. This describes us perfectly. Make sure that this guarantee is totally transparent.

### Zero-plagiarism guarantee

Each paper is composed from scratch, according to your instructions. It is then checked by our plagiarism-detection software. There is no gap where plagiarism could squeeze in.

### Free-revision policy

Thanks to our free revisions, there is no way for you to be unsatisfied. We will work on your paper until you are completely happy with the result.

Your email is safe, as we store it according to international data protection rules. Your bank details are secure, as we use only reliable payment systems.

### Fair-cooperation guarantee

By sending us your money, you buy the service we provide. Check out our terms and conditions if you prefer business talks to be laid out in official language.

Order your essay today and save 10% with the coupon code: best10