Who understands Simple Random Sample (SRS)am having some time understanding it pplease need some help?
First, the question you ask must make some sense. For the US, there is no "war in Iraq." http://en.wikipedia.org/wiki/Withdrawal_... indicates: "The withdrawal of American military forces from Iraq began in June 2009 and was completed by December 2011, bringing an end to the Iraq War." The question might make some sense if it were worded: "Do you believe that the US war in Iraq created conditions that will eventually lead to peace in the middle east?" But, even here, the answer to the question is too obviously "No." But, to answer your question... You must ensure a "random" sample of the population. One way to do this is to get a computer list of all parents and randomly select your sample using random numbers assigned to each parent. Or you could take every N'th parent on the list as your sample. Once you complete the survey, the standard error of the sample average is the standard deviation of the sample divided by the square root of the sample size. The larger the sample size, the smaller the standard error. You would expect the sample average to be within 2 standard errors of the population mean about 95% of the time.
According to the results of the 2004 presidential election, 59% of New Yorkers voted for Kerry. Imagine the se?
a) .590 b) sqrt[(0.59)(0.41)] =.492 ------------- d) Mean μ = 0.59 Standard deviation σ = 0.4918 Standard error σ / √ n = 0.4918 / √ 100 = 0.04918 standardize xbar to z = (xbar - μ) / (σ / √ n ) P(xbar > 0.65) = P( z > (0.65-0.59) / 0.04918) = P(z > 1.22) = .1112 (from normal probability table) e) Mean μ = 0.59 Standard deviation σ = 0.4918 Standard error σ / √ n = 0.4918 / √ 100 = 0.04918 standardize xbar to z = (xbar - μ) / (σ / √ n ) P( 0.55 < xbar < 0.65) = P[( 0.55 - 0.59) / 0.04918 < z < ( 0.65 - 0.59) / 0.04918] P( -0.8133 < z < 1.22) = .8888 - .2090 = .6798 (from normal probability table) f) The z-values correspong to the middle 90% are 1.645 and -1.645 from the normal probability table. Standard error σ / √ n = 0.4918 / √ 100 = 0.04918 1.645= (x-.59) / 0.04918 x = (1.645)( 0.04918)+.59 =.671 .59 -(1.645)( 0.04918) =.509 The middle 90% of all sample proportions p^^\^ fall between .509 and .671
How much does Duolingo help to master speaking a new language if you have finished the majority of it?
I am 4 bubbles away from finishing the Spanish tree! It's a great way to start learning Spanish: light, easy, almost pain-free. I started with Duolingo Spanish maybe one year ago, after trying to learn Spanish for two years from textbooks by myself without much success. I could hardly speak Spanish when I started Duolingo, and now my spoken Spanish is at intermediate level. Several things I like about Duolingo (Spanish):It is great for killing the few minutes of bus-waiting time everyday. I spent very little extra effort on my Spanish. I like the spaced repetition feature, so I know it is OK if I can't remember everything at one go. I will see them again soon. (I keep all my past bubbles at full strength, even if it means I make slower progress). The Spanish in Duolingo is quite up-to-date and international (compared to one of my books that might date back to Medieval Spain).Clear and accurate pronunciation (which I repeat after until I can say the sentences fluently). However, once you past the beginer level, you will need something more than Duolingo to really learn to use the language. I started taking speaking lessons online on iTalki.com two months ago. The vocabulary and the feeling for the language I built up using Duolingo definitely help me to progress much faster and to feel more comfortable speaking.
Standard normal distribution help in stats?
The National Assessment of Educational Progress (NAEP) gave a test of basic arithmetic and the ability to apply it in everyday life to a sample of 840 men 21 to 25 years of age. Scores range from 0 to 500; for example, someone with a score of 325 can determine the price of a meal from a menu. The mean score for these 840 young men was [x] = 272. We want to estimate the mean score μ in the population of all young men. Consider the NAEP sample as an SRS from a Normal population with standard deviation σ = 60. (a) If we take many samples, the sample mean [x] varies from sample to sample according to a Normal distribution with mean equal to the unknown mean score μ in the population. What is the standard deviation of this sampling distribution? (b) According to the 68 part of the 68-95-99.7 rule, 68% of all values of [x] fall within _______ on either side of the unknown mean μ. What is the missing number? (c) What is the 68% confidence interval for the population mean score μ based on this one sample? Note: Use the 68-95-99.7 rule to find the interval.
Chemistry 2-Which molecule has highest melting point?
Hello! Short answer: MgO with a melting point of 2852 degrees C has the highest melting point. (melting points in celsius) CO2 -78 SrS 2002 Xe -111.8 (NH4)2CO3 58 F2 -220 MgO 2852 Longer explanation: the main component that determines melting point is intermolecular forces. From the examples above, we see that lone atoms and molecules with covalent bonds have very low melting points. Ionic compounds like magnesium oxide and strontium sulfur have ionic forces acting on them, creating higher melting points than their covalent counterparts. Other factors, though not as strong as the ionic bond, include (in general): Size of molecule: Larger molecules have higher melting points. Symmetry of molecule: the more symmetrical, the higher the melting point. Note: if you are curious as to how you could have predicted MgO has a higher melting point than SrS, despite the fact that they are both ionic, you need to look at an electronegativity chart. Mg has electronegativity 1.3 while O is 3.5, for a difference of 2.2. Sr has electronegativity 1.0 while S is 2.5, for a difference of 1.5. Since the MgO is more ionic, we could have predicted that it would have the higher melting point! I hope that helps!!!
How long would it take for a teenager to become fluent in Italian?
I was 13 when I started learning Italian. I am South African and had virtually no one to talk to, except my school's polyglot English teacher who assisted me. I learnt Italian in order to understand opera (my big passion in life) better. I had the additional benefit of also learning Latin at school, which helped my Italian tremendously.I used an Italian grammar book and whenever I heard Italian in Cape Town, I would go and speak to the people. I even befriended an Italian conductor who frequently conducted opera in Cape Town at the time.After around 3 months I could start having simple conversations and understand operas. It wasn't until 8 years later (1993) that I went to Italy and could put my Italian in practice. However, the real value of my Italian only came about in 2000 when I went to work in Brazil and Italian helped me with Portuguese. I lived in Sao Paulo which has a large Italian population. In the beginning there were enough people who could speak Italian that I could get around speaking Italian. Eventually, however, Portuguese started replacing Italian in my head. Nowadays when I speak Italian I have to make an effort not to use Portuguese words. In fact, once some Italians told me that I speak Italian like any Brazilian who learnt Italian (in other words, I was making the same mistakes that Brazilians and Portuguese make when they speak Italian). Having said that, I got around quite well during another vacation to Italy in 2013. I found a totally different Italy, though, from 1993. In 1993 I had the Coliseum and Roman Forum almost all to myself. In 2013 I had to share them with thousands of other tourists.Anyway, you're young. You won't learn Italian like a baby would, but within three months of daily study you should be able to start speaking.
I'm so confused. Please help me. Null and alternative hypotheses. Test statistic and p-value?
Hypothesis Test for mean: Assuming you have a large enough sample such that the central limit theorem holds, or you have a sample of any size from a normal population with known population standard deviation, then to test the null hypothesis H0: μ ≤ Δ or H0: μ ≥ Δ or H0: μ = Δ Find the test statistic z = (xbar - Δ ) / (sx / √ (n)) where xbar is the sample average sx is the sample standard deviation, if you know the population standard deviation, σ , then replace sx with σ in the equation for the test statistic. n is the sample size The p-value of the test is the area under the normal curve that is in agreement with the alternate hypothesis. H1: μ > Δ; p-value is the area to the right of z H1: μ < Δ; p-value is the area to the left of z H1: μ ≠ Δ; p-value is the area in the tails greater than |z| If the p-value is less than or equal to the significance level α, i.e., p-value ≤ α, then we reject the null hypothesis and conclude the alternate hypothesis is true. If the p-value is greater than the significance level, i.e., p-value > α, then we fail to reject the null hypothesis and conclude that the null is plausible. Note that we can conclude the alternate is true, but we cannot conclude the null is true, only that it is plausible. The hypothesis test in this question is: H0: μ ≤ 1 vs. H1: μ > 1 The test statistic is: z = ( 1.05 - 1 ) / ( 0.13 / √ ( 20 )) z = 1.720052 The p-value = P( Z > z ) = P( Z > 1.720052 ) = 0.04271147 Since the p-value is less than the significance level we reject the null hypothesis and conclude the alternate hypothesis μ > 1 is true.
In a group of 50 students, 31 are taking French, 17 are taking Spanish, and 10 are taking neither French nor Spanish. How many students are taking both French and Spanish?
total persons:50speaking French:31speaking spanish:17neither speaking any languages:10then,number of persons speaking both languages:50—10=40then,n(French U Spanish)=31+17—n(speaking both the languages)40=31+17—nn=48—40n=8