Statistics Help: Answers to Questions & Explanations

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The discussion revolves around a request for help with various statistics problems, including calculating probabilities for mutually exclusive events, binomial distributions, and normal distributions. Specific questions involve determining the likelihood of events occurring, expected purchases based on customer behavior, and computing z-scores for labor costs. Participants emphasize the importance of attempting the homework independently to enhance understanding. The overall tone suggests a collaborative effort to clarify statistical concepts while encouraging personal engagement with the material.
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I need help on the following Questions that I'm working on. Can someone explain to me and show me how they came up with the answers. Thank you.

:confused:


#1

The events X and Y are mutually exclusive. Suppose P(X) = .05 and P(Y) = .02. What is the probability of either X or Y occurring? What is the probability that neither X nor Y will happen?


#2

If you ask three strangers on campus, what is the probability: (a) All were born on Wednesday? (b) All were born on different days of the week? (c) None were born on a Saturday?

#3

In a binomial situation n=5 and pie = .40 Determine the probabilities of the following events using the binomial formula.

a. x = 1

b. x = 2


#4

Steele Electronics, Inc. sells expensive brands of stereo equipment in several shopping malls throughout the northwest section of the United States. The Marketing Research Department of Steele reports that 30 percent of the customers entering the store that indicate they are browsing will, in the end, make a purchase. Let the last 20 customers who enter the store be a sample.

a. How many of these customers would you expect to make a purchase

b. What is the probability that exactly five of these customers make a purchase?

c. What is the probability ten or more make a purchase?

d. Does it seem likely at least one will make a purchase?



#5

A recent article in the Myrtle Beach Sun Times reported that the mean labor cost to repair a color TV is $90 with a standard deviation of $22. Monte’s TV Sales and Service completed repairs on two sets this morning. The labor cost for the first was $75 and it was $100 for the second. Compute z values for each and comment on your findings.


#6

The mean starting salary for college graduates in the spring of 2000 was $31,280. Assume that the distribution of starting salaries follows the normal distribution with a standard deviation of $3,300. What percent of the graduates have starting salaries:

a. Between $30,000 and $35,0000

b. More than $40,000

c. Between $35,000 and $40,000
 
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1. Look up the definitoins.
2. think about it a little
3. what's x?
4. see 2.
5. what's z?
6. use the formulae even though the assumptions are ridiculous.


sorry, but the questions that make sense are failrly easy, and this is obviously homework, and a lot more good will come if you try ther homework yourself, perhaps seying what you've done will demonstrate you've tried it at least in part.
 
I was reading documentation about the soundness and completeness of logic formal systems. Consider the following $$\vdash_S \phi$$ where ##S## is the proof-system making part the formal system and ##\phi## is a wff (well formed formula) of the formal language. Note the blank on left of the turnstile symbol ##\vdash_S##, as far as I can tell it actually represents the empty set. So what does it mean ? I guess it actually means ##\phi## is a theorem of the formal system, i.e. there is a...
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