STAT 13

(Sec. 1a-1c)

Introduction to Statistical Methods for the Life and Health Sciences

Instructor: Ivo Dinov, Asst. Prof.

Departments of Statistics & Neurology

Due Date:

See the HW submission rules. On the front page include the following header.

HW_4_1

The following table of probabilities was obtained from STATA: Normal with mean μ= 8.6 and standard deviation σ= 1.28.

mean

8.6

standard deviation

1.28

(i) What is the least amount of soft serve ice cream that is needed so that the driver can satisfy demand on 90% of afternoons?

Use either STATA or a graphics calculator to solve the following problems where X~Normal(μ = 5.1, σ² = 0.87² ):

X has a mean of -3 and a standard deviation of 5 and W has a mean of 5 and a standard deviation of 3. Let X and W be independent random variables and let Y = 3X - 3W.

(ii) What can we say about the shape of the distribution of Y?

(HW_4_2) Suppose that X~ Normal(μ=3, σ²=16) compute the Z-scores for the following numbers and state how many SD's each of these numbers is away from μ:

-5
11
5
1.4
What is the probability P(-3 ≤ X ≤ -1)? Is it different from P(-3 < X < -1)? Why?

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Ivo D. Dinov, Ph.D., Departments of Statistics and Neurology, UCLA School of Medicine