1.  You want to obtain a sample to estimate how much parents spend on their kids birthday parties. Based on previous study, you believe the population standard deviation is approximately σ=26.2σ=26.2 dollars. You would like to be 99% confident that your estimate is within 2 dollar(s) of average spending on the birthday parties. How many parents do you have to sample?

2. You measure 27 watermelons' weights, and find they have a mean weight of 30 ounces. Assume the population standard deviation is 7.4 ounces. Based on this, what is the maximal margin of error associated with a 90% confidence interval for the true population mean watermelon weight.

Give your answer as a decimal, to two places

3.

Statistics students in Oxnard College sampled 11 textbooks in the Condor bookstore and recorded the number of pages in each textbook and its cost. The bivariate data are shown below:

A student calculates a linear model
yy =  xx + . (Please show your answers to two decimal places)
Use the model to estimate the cost when number of pages is 949.
Cost = $ (Please show your answer to 2 decimal places.)

4.

Statistics students in Oxnard College sampled 11 textbooks in the Condor bookstore and recorded the number of pages in each textbook and its cost. The data are shown below:

A student calculates a linear model using technology (TI calculator)
ˆyy^ =  xx + . (Please show your answers to two decimal places)
Use the model to estimate the cost when number of pages is 574.
Cost = $ (Please show your answer to 2 decimal places.)

For MSE (mean square error), why is it important to to know the parameters of the distribution of the sample values of the attributes used for the observations ? please provide example and a thorough explanation. Please explain why we need to know the parameter to calculate MSE

1. You want to obtain a sample to estimate a population proportion. At this point in time, you have no reasonable preliminary estimation for the population proportion. You would like to be 95% confident that you estimate is within 3% of the true population proportion. How large of a sample size is required?

2. A political candidate has asked you to conduct a poll to determine what percentage of people support her. If the candidate only wants a 8% margin of error at a 90% confidence level, what size of sample is needed

3. You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately σ=45.1σ=45.1. You would like to be 98% confident that your estimate is within 4 of the true population mean. How large of a sample size is required?

4. You want to obtain a sample to estimate how much parents spend on their kids birthday parties. Based on previous study, you believe the population standard deviation is approximately σ=51.3σ=51.3 dollars. You would like to be 95% confident that your estimate is within 1.5 dollar(s) of average spending on the birthday parties. How many parents do you have to sample?

Number of days that would result in​ 99% probability of completion​

prove

p(aUbUc)= p(a}+P(b)+p(c)-p{ab)-p(ac)+p(abc)

What is significance good for? Which of the following questions does a test of significance answer? Briefly explain your replies. (a)Is the sample or experiment properly designed? (b)Is the observed effect due to chance? (c)Is the observed effect important?

(a)Is the sample or experiment properly designed?

(b)Is the observed effect due to chance?

(c)Is the observed effect important?

The answer choices below represent different hypothesis tests. Which of the choices are left-tailed tests? Select all correct answers. Select all that apply: H0:X=17.3, Ha:X≠17.3 H0:X≥19.7, Ha:X<19.7 H0:X≥11.2, Ha:X<11.2 H0:X=13.2, Ha:X≠13.2 H0:X=17.8, Ha:X≠17

(9pt) A stock market analyst wants to determine if the recent introduction of the IPhone 8x has changed the distribution of shares in the cellphone market. The analyst collects data from a random sample of 300 cellphone customers. The table below shows the observed customers’ share of cellphones (fi ). When using this random sample, the analyst needs to be 95% confident of test results. The hypothesis to be tested follows: H0 : Plg =0.20; Pa =0.32; Ps =0.48 ; market shares have remained same Ha : Plg ≠0.20; Pa ≠0.32; Ps ≠0.48 ; market shares have changed Cellphone company Current Market Share Observ. fi Samsung 0.48 100 Apple 0.32 120 LG 0.20 80 Totals 300 a. (6pt) Compute the test statistic for a chi-squared test. b. (3pt) After the test, would you conclude that the introduction of the IPhone 8x has changed the market composition? Why?

Given the following frequency distribution, the distribution is:

Answer: Which one it is?

Of the 93 participants in a drug trial who were given a new experimental treatment for​ arthritis, 53 showed improvement. Of the 92 participants given a​ placebo, 48 showed improvement. Construct a​ two-way table for these​ data, and then use a 0.05 significance level to test the claim that improvement is independent of whether the participant was given the drug or a placebo. Complete the following​ two-way table.

Two samples are taken with the following numbers of successes and sample sizes
r1r1 = 25 r2r2 = 24
n1n1 = 71 n2n2 = 67

Find a 98% confidence interval, round answers to the nearest thousandth.
____< p1−p2p1-p2 <____

Explain the following:

• Concepts of Hypothesis Testing
• Hypotheses Test for a population mean
• Hypothesis test for a population proportion
• Test of normality
• Chi-Square Test for Independence

Suppose there are two one-year assets. You cannot buy a fractional portion of either asset. Asset A costs $100 to buy and in one year pays a total of either $120 or $90, with equal probability. Asset B costs $200 to buy and in one year pays a total of either $180 or $240. When Asset A pays $120, Asset B pays $180 (and when Asset A pays $90, asset B Pays $240). You buy two of Asset A and one of asset B. What is the standard deviation of the rate of return on your investment? (Hint: define a new asset C = 2A +B). Express your answer in decimal form without a percent sign and rounded and accurate to 4 decimal place.

Three years ago you bought 200 shares of stock trading at $40 per share. One year after you bought the stock, it paid a dividend of $2 per share, which you then immediately reinvested in additional (fractional) shares of stock (at a price of $45 per share, which was the price immediately after the dividend was paid). There were no other dividends or cash flows, and today the stock sells for $52 per share. What is the annualized time-weighted return (i.e, geometric average annual return or CAGR)? Express your answer in decimal form, rounded and accurate to 5 decimal places (e.g., 0.12345).

(5) Suppose x has a distribution with μ = 20 and σ = 16.

(a) If a random sample of size n = 47 is drawn, find μ_x, σ_x and P(20 ≤ x ≤ 22). (Round σ_x to two decimal places and the probability to four decimal places.)

μ_x =

σ _x =

P(20 ≤ x ≤ 22)=

(b) If a random sample of size n = 61 is drawn, find μ_x, σ_x and P(20 ≤ x ≤ 22). (Round σ_x to two decimal places and the probability to four decimal places.)

μ_x =

σ _x =

P(20 ≤ x ≤ 22)=

c) Why should you expect the probability of part (b) to be higher than that of part (a)? (Hint: Consider the standard deviations in parts (a) and (b).)
The standard deviation of part (b) is (Blank)?  part (a) because of the ( Blank) ? Sample size. Therefore, the distribution about μ_x is (Blank) ?

(8) Let x be a random variable that represents the level of glucose in the blood (milligrams per deciliter of blood) after a 12 hour fast. Assume that for people under 50 years old, x has a distribution that is approximately normal, with mean μ = 54 and estimated standard deviation σ = 11. A test result x < 40 is an indication of severe excess insulin, and medication is usually prescribed.

(a) What is the probability that, on a single test, x < 40? (Round your answer to four decimal places.)

(b) Suppose a doctor uses the average x for two tests taken about a week apart. What can we say about the probability distribution of x? Hint: See Theorem 6.1.

What is the probability that x < 40? (Round your answer to four decimal places.)

(c) Repeat part (b) for n = 3 tests taken a week apart. (Round your answer to four decimal places.)

(d) Repeat part (b) for n = 5 tests taken a week apart. (Round your answer to four decimal places.)

Explain what this might imply if you were a doctor or a nurse.

(9) Let x represent the dollar amount spent on supermarket impulse buying in a 10-minute (unplanned) shopping interval. Based on a certain article, the mean of the x distribution is about $27 and the estimated standard deviation is about $9.

(a) Consider a random sample of n = 100 customers, each of whom has 10 minutes of unplanned shopping time in a supermarket. From the central limit theorem, what can you say about the probability distribution of x, the average amount spent by these customers due to impulse buying? What are the mean and standard deviation of the x distribution?

Is it necessary to make any assumption about the x distribution? Explain your answer.

(b) What is the probability that x is between $25 and $29? (Round your answer to four decimal places.)

(c) Let us assume that x has a distribution that is approximately normal. What is the probability that x is between $25 and $29? (Round your answer to four decimal places.)

(d) In part (b), we used x, the average amount spent, computed for 100 customers. In part (c), we used x, the amount spent by only one customer. The answers to parts (b) and (c) are very different. Why would this happen?

(10) A European growth mutual fund specializes in stocks from the British Isles, continental Europe, and Scandinavia. The fund has over 325 stocks. Let x be a random variable that represents the monthly percentage return for this fund. Suppose x has mean μ = 1.4% and standard deviation σ = 1.1%.

(a) Let's consider the monthly return of the stocks in the fund to be a sample from the population of monthly returns of all European stocks. Is it reasonable to assume that x (the average monthly return on the 325 stocks in the fund) has a distribution that is approximately normal? Explain.

(Blank)  x is a mean of a sample of n = 325 stocks. By the(Blank)  the x distribution( Blank) approximately normal?

(b) After 9 months, what is the probability that the average monthly percentage return x will be between 1% and 2%? (Round your answer to four decimal places.)(c)After 18 months, what is the probability that the average monthly percentage return x will be between 1% and 2%? (Round your answer to four decimal places.

(d) Compare your answers to parts (b) and (c). Did the probability increase as n (number of months) increased? Why would this happen?

(e) If after 18 months the average monthly percentage return x is more than 2%, would that tend to shake your confidence in the statement that μ = 1.4%? If this happened, do you think the European stock market might be heating up? (Round your answer to four decimal places.)  P(x > 2%)

Explain.