hockeyplayer42
New member
- Joined
- May 10, 2010
- Messages
- 8
Hi, i've attempted these several problems with different formulas. I am not looking for someone to answer each problem for me, rather help me through however many they'd like to help me with. Ive finished 13/20 other questions. If you can help me out at all please do! I have no where else to go for help lol
1(a)Let Y have a binomial distribution with parameters n and p. We reject Ho: p=1/2 and accept H1: p>1/2 if Y>=c. Find n and c such that the probability of a Type I error is .10, and P(reject Ho/p=2/3)=.95.
(b)What is the probability of a Type II error?
I dont know how to solve for n and c, but the confidence must be .9 since error 1 is .10. I dont know what to do next.
2.Let xbar be the observed mean of a random sample of size n from a distribution having mean mu and variance sigma squared. Find n so that xbar-sigma/4 to xbar+sigma/4 is an approximate 95% confidence interval for mu.
I figured i had to find the zscore for this problem and solve for n possibly with the E formula. (Error) I dont know what to do next.
3. Let p denote the probability that, for a particular tennis player, the first serve is good. Since p=0.40 this player decided to take lessons in order to increase p. When the lessons are completed, the hypothesis Ho
=0.40 will be tested against H1>0.40 based on n=25 trials. Let y equal the number of first serves that are good, and let the critical region be defined by C={y:y>=13}. Determine the significance level.
I know typically significance level is .05 or .025, but i dont know. I assume i need to work with a T-test since N is less than 30, so degrees of freedom is 24. Where do i go from here.
4. Let X be N(mu,sigma squared)so that P(X<89)=0.90 and P(X<94)=0.95. Find mu and sigma squared.
Do i cancel out or something, P(x<89-mu/sigma)=.90 and P(x<94-mu/sigma)=.95
5. Let X1,...,X9 be a random sample of size 9 from a distribution that is N(mu,sigma squared). If sigma is known, find the length of a 95% confidence interval for mu if this interval is based on the random variable Squarert9(xbar-mu)/sigma.
So confidence is obviously 95%, so do i SquarRt9(xbar-mu/sigma)=.95? I dont know what i do with N=9
6. Half pint (8oz) milk cartons are filled at a dairy by a filling machine. To provide a check on the machine, a sample of 10 cartons is periodically measured. If the sample mean deviates by more than a certain amount d from the nominal value 8oz, i.e, if [xbar-8]>d, then the machine setting is adjusted. The chance of a false alarm indicating an unnecessary adjustment is to be limited to 1%. Find a formula for d.
I am assuming the Confidence is 99%, is significance level 1%? N=10, so do i do something with a T-test statistic where degrees of freedom is 9?
7. The lifetime of lightbulbs of a particular type are normally distributed with a mean of 293 hours and a standard deviation of 6 hours. Find the 1st quartile.
This question seems real easy, but how would i figure out a quartile of a mean of 293 without a list of numbers? Or do i simply create a list of numbers that mean to 293. But what about S.D=6?
1(a)Let Y have a binomial distribution with parameters n and p. We reject Ho: p=1/2 and accept H1: p>1/2 if Y>=c. Find n and c such that the probability of a Type I error is .10, and P(reject Ho/p=2/3)=.95.
(b)What is the probability of a Type II error?
I dont know how to solve for n and c, but the confidence must be .9 since error 1 is .10. I dont know what to do next.
2.Let xbar be the observed mean of a random sample of size n from a distribution having mean mu and variance sigma squared. Find n so that xbar-sigma/4 to xbar+sigma/4 is an approximate 95% confidence interval for mu.
I figured i had to find the zscore for this problem and solve for n possibly with the E formula. (Error) I dont know what to do next.
3. Let p denote the probability that, for a particular tennis player, the first serve is good. Since p=0.40 this player decided to take lessons in order to increase p. When the lessons are completed, the hypothesis Ho
=0.40 will be tested against H1>0.40 based on n=25 trials. Let y equal the number of first serves that are good, and let the critical region be defined by C={y:y>=13}. Determine the significance level.I know typically significance level is .05 or .025, but i dont know. I assume i need to work with a T-test since N is less than 30, so degrees of freedom is 24. Where do i go from here.
4. Let X be N(mu,sigma squared)so that P(X<89)=0.90 and P(X<94)=0.95. Find mu and sigma squared.
Do i cancel out or something, P(x<89-mu/sigma)=.90 and P(x<94-mu/sigma)=.95
5. Let X1,...,X9 be a random sample of size 9 from a distribution that is N(mu,sigma squared). If sigma is known, find the length of a 95% confidence interval for mu if this interval is based on the random variable Squarert9(xbar-mu)/sigma.
So confidence is obviously 95%, so do i SquarRt9(xbar-mu/sigma)=.95? I dont know what i do with N=9
6. Half pint (8oz) milk cartons are filled at a dairy by a filling machine. To provide a check on the machine, a sample of 10 cartons is periodically measured. If the sample mean deviates by more than a certain amount d from the nominal value 8oz, i.e, if [xbar-8]>d, then the machine setting is adjusted. The chance of a false alarm indicating an unnecessary adjustment is to be limited to 1%. Find a formula for d.
I am assuming the Confidence is 99%, is significance level 1%? N=10, so do i do something with a T-test statistic where degrees of freedom is 9?
7. The lifetime of lightbulbs of a particular type are normally distributed with a mean of 293 hours and a standard deviation of 6 hours. Find the 1st quartile.
This question seems real easy, but how would i figure out a quartile of a mean of 293 without a list of numbers? Or do i simply create a list of numbers that mean to 293. But what about S.D=6?