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Normal Distribution

Problems on sampling, hypothesis testing and confidence interval

1.Which of the following statements about the sampling distribution of the sample mean is incorrect? a. The sampling distribution of the sample mean is approximately normal whenever the sample size is sufficiently large (n>30). b. The sampling distribution of the sample mean is generated by repeatedly taking samples of size n

Probability: Standard Deviation, Exponential Distribution and Expected Values

(8) 1. A manufacturer of electronics products expects that 1% of units fail during the warranty period. A sample of 600 independent units is tracked for warranty performance. a) What is the expected number of failures during the warranty period? b) What is the probability that none fails during the warranty period? c) What is

Multiple choice questions on Normal Distribution, Time Value of Money

1.Consider the normal distributions drawn below (with different scales) They both have m = 20 and the area of the shaded region of each is 0.90. Which of the following holds? a. x1 < x2 b. x1 > x2 c. x1 = x2 d. There is not enough information e. x1 >= x2 2.If you deposit $5000 into a fund paying 6% interest compou

Probability using normal distribution.

H.) The length of time it takes a student to find a parking spot on campus follows normal distribution of mean, 3.5 minutes. The probability that a student will find a spot in less than 3 minutes is: 1.) 0.8085 2.) 0.1915 3.) 0.3085 4.) 0.6915

Case Study using normal distribution

A company supplies pins in bulk to a customer. The company uses an automatic lathe to produce the pins. Due to many causes - vibration, temperature, wear and tear, and the like - the lengths of the pins made by the machine are normally distributed with a mean of 1.012 inches and a standard deviation of 0.018 inch. The custome

Significance Testing Format

The most important material reclaimed from beverage bottles is PET plastic. A serious impurity is aluminum, which later can clog the filters in extruders when the recycled material is used. The following are the amounts (in ppm by weight of aluminum) found in bihourly samples of PET recovered at the plant over roughly a two day

Standard Normal Distribution Table

Use the Normal Table to find the following: a) Probability (z < -2.65) b) Probability (z > -1.55) c) Probability (-2.00 < z < 2.25) d) Probability ( 1.25 < z < 2.40) Please show the steps you used to get to the answers.

Find Percentiles from a Given Normal Distribution

Your firm is attempting to reduce its cost of maintenance of customers by culling the least-productive of them. A census of sales records was undertaken and it was determined that the mean level of sale of all customers was $235,000 with a standard deviation of $15,000. (a) It is your desire to eliminate from your customer po

Statistics: Normal Distribution

*Please see attachment for case study. Questions: (a) What are the observational units and variable units of interest in this study? Also specify the population or process of interest. (b) State and null and an alternative hypothesis about the value of pi (in words and symbols) (c) We can assess the strength of evide

Normal distribution

6.12 a. The area under the standard normal curve with parameters m = 64.4 and o= 2.4 that lies to the left of 61 is 0.0783. Use this information to estimate the percentage of female's students who are shorter than 61 inches. 6.14 According to the National Health and Nutrition Examination Survey, the serum (noncellular portio

Using Excel to make plots of Gaussian distribution

I am using Analytical Chemistry 7th edition By Skoog, West, Holler, and Crouch. please let me know if any additional info. is needed. There is a sample of the graph in the book Chapter 6 and 7. Using Excel, construct a spreadsheet to make two plots of a Gaussian distribution: 1. relative frequency vs deviation from the mean

Normal Distribution; Mean; Standard Deviation Functions

I am having trouble with PART B of this problem. Here is the whole problem: Assume body temperatures are normally distributed with mean of 98.2 and a standard dev. of 0.62 Part A) Assuming a hospital defines a fever as 100 or over, determine the percentage of a normal healthy person considered to have a fever using Z tabl


Question 1 If a normal distribution of empirical scores is converted to a distribution of z scores: A. The new mean will be zero B. The new standard deviation will be one C. Both A and B D. Neither A and B. Question 2 Milquetoasts gracious statistics professor at Northwestern announced that he would drop th

Stats 5

The management of White Industries is considering a new method of assembling its golf cart. The present method requires 42.3 minutes, on the average, to assemble a cart. The mean assembly time for a random sample of 24 carts, using the new method, was 40.6 minutes, and the standard deviation of the sample was 2.7 minutes. Usi

Finding percentiles of known normal distributions

All standard IQ test scores are normally distributed and are set up so that the mean score is 100. However, the standard deviation differs from test to test. For example, the standard deviation on the Otis-Lennon test is 16, while the Cattell's standard deviation is 24. The following are three famous high IQ societies, with t

Find the Critical Values and Determine the Appropriate Distribution

Do one of the following as appropriate: a) Find the critical value t (alpha/2) b) Find the critical value z (alpha/2) c) State that neither the normal nor the t distribution applies. Problem: 95%; n= 40; sigma is unknown; population appears to be skewed. (See attachment for complete question and symbols that did not come

Distribution Function Requirements

How do I know which distribution to use for the following and when/where do tables apply?: Nonstandard Normal Binomial Normal Standard normal Central limit theorem a) Mean is 0, stand. dev. is 0 degrees C., find P between 0.05 and 1.50 b)Mean is 63.6 and s.d. is 2.5; Club had requirement that women must be 70 inches

Normal Distribution SAT Scores

The average score on the math portion of the SAT was 516 in 2002. suppose that the math score of all students taking the SAT 2002 were normally distributed with a mean of 516 and a standard deviation of 90. a) what percentage of the students scored higher than 600 on this exam? b) what percentage of the students scored lower t

Proportion of the Shaft in an Optical Storage Drive

The diameter of a shaft in an optical storage drive is normally distributed with mean 0.2508 inch and standard deviation 0.0005inch. The specifications of the shaft are 0.2500+/-0.0015 inch. a.) What proportion of the shafts conforms to specifications? b.) What can be done to reduce non-conforming proportion?

Random Sample Population Variance

A. n=17. Find P(t<-1.746) aa) .05 bb).95 cc).45 dd) 1.0 B. A random sample of 64 observations is observed from a population of SAT scores in 2001. Which of the following is a correct statement? aa) It is the distribution of the observed 64 SAT scores. bb) X-bar is approximately normal. cc) The mean of all possible x-bars is ave

Only for 103997

Only for above listed OTA. Last one for this semester. Thank you. Hope you're around mid- June through July. Have a great summer! Problem: In a stan. normal distribution, find the z-score that separates the top 20% area from the bottom 80%.

Estimated percentile rank

Tthe mean for a special distribution is 100 and the standard deviation is 15. What is the estimated percentile for an individual who had a score of 90 on this scale?

Questions from Textbook: Statistics for Management (7th Ed. ) Levin & Rubin

1). In a normal distribution with a standard deviation of 5.0, the probability that an observation selected at random exceeds 21 is 0.14 (14%). a). Find the mean of the distribution. b). Find the value of below which 4 percent of the values in the distribution lie. 2). The company's manager calculates that it requires

Normally dist with mean and SD

Nurses saleries are Normally distributed with mean of 35,000 and standard deviation$1700. A. What is the probability that a nurse earn more than $36,000? B. What is the probality that a group of 10 nurses have mean salary greater than $36,000? c. What salary does a nurse need to earn to have a salary in the top 25% of nurses'

Distribution Elementary Statistics

I need some serious explanation. I cannot even understand what to study for the frist 6 questions on the test about the formula I posted in this subject line. The book I am using is Elementary Statistics by mario F. Triola. 8th edition. Here is what I am to study: Students will have 2 hours to answer 20 exam questions.

Normal Distribution problem

The amounts dispensed by a cola machine follow the normal distribution with a mean of 7 ounces and a standard deviation of 0.10 ounces per cup. How much cola is dispensed in the largest 1 percent of the cups?

Hypothesis in statistics

A light bulb manufacturer advertises that the average life for their light bulbs is 800 hours. A random sample of 15 of their light bulbs resulted in the following data, in hours; 990 841 953 612 727 800 686 594 835 897 943 791 750 667 723 Assume that the bulb life is normally distributed. At the 10% significance level, do

Estimation using Normal distribution

In the last municipal election, a sample of 350 registered voters showed that 85 voted for the incumbants. Find a 98% confidence interval estimate for the proportion of all voters voting for the incumbants.

Estimation using Normal Distribution

A random sample of 55 adults in a certain country showed an average height of six feet (72 inches) for adults. Statistics show the population standard deviation to be 3.40 inches. Calculate the 95% confidence interval for the mean height of the adult population.