A publishing company wanted to test whether typing speed differs when using word processor A or word processor B. A random sample of 25 typists was selected and the typing speeds (in words per minute) were recorded for each secretary when using word processor A and then when using word processor B. (Which word processor was used first was determined for each typist by a coin flip).Based on the collected data, a 95% confidence interval for μd, the mean difference (word processor A - word processor B) was found to be (2.5, 7.8).The appropriate hypotheses for testing whether the typing speeds differ when using word processor A or word processor B is the two-sided test:Based on this confidence interval for μd, what would be your conclusion (at the .05 significance level)? Explain.

Interpret the 95% confidence interval in context. Make sure that your interpretation quantifies the effect that the type of word processor used (the explanatory variable, X) has on the typing speed (the response variable, Y).

A tech company claims that their new software reduces the average time taken to process a specific task by 2 minutes compared to the existing software in the market. An independent tech reviewer wants to test this claim. They conduct an experiment with 40 users. Half of them use the new software, and the other half use the existing software. The differences in processing times (new software - existing software) are recorded for each user. The sample mean difference is found to be 1.5 minutes with a standard deviation of 1.2 minutes. Test the company's claim at a 1% significance level.

A study was conducted to estimate μ, the mean number of weekly hours that U.S. adults use computers at home. Suppose a random sample of 81 U.S. adults gives a mean weekly computer usage time of 8.5 hours and that from prior studies, the population standard deviation is assumed to be σ = 3.6 hours. The 95% confidence interval for the mean, μ, is (7.7, 9.3).Which of the following will provide a more informative (i.e., narrower) confidence interval than the 95% confidence interval? Check all that apply. Using a sample of size 400 (instead of 81) Using a sample of size 36 (instead of 81) Using a different sample of size 81 Using a 90% level of confidence (instead of 95%) Using a 99% level of confidence (instead of 95%)

Suppose a grocery store is considering the purchase of a new self-checkout machine that will get customers through the checkout line faster than their current machine. Before he spends the money on the equipment, he wants to know how mu faster the customers will check out compared to the current machine. The store manager recorded the checkout times, in seconds, for a randomly selected sample of checkouts from each machine. The summary statistics are provided in the tabl \[ \text { df }=90.71233 \] Compute the lower and upper limits of a95%confidence interval to estimate the difference of the mean checkout times fo customers. Estimate the difference for the old machine minus the new machine, so that a positive result reflects faster chec times with the new machine. Use the Satterthwaite approximate degrees of freedom, 90.71233 . Give your answers precise least three decimal places.

A group of researchers working in Europe, Asia, and Oceania conducted a study to determine how quickly different Eurasian languages are typically spoken (in syllables per second) and how much information they can effectively convey (in bits per second). They found that, although languages vary widely in the speed at which they are spoken, the amount of information languages can effectively convey tends to vary much less. Thus, they claim that two languages with very different spoken rates can nonetheless convey the same amount of information in a given amount of time. Which choice best describes data from the table that support the researchers’ claim?A) Among the five languages in the table, Thai and Hungarian have the lowest rates of speech and the lowest rates of information conveyed.B) Vietnamese conveys information at approximately the same rate as Spanish despite being spoken at a slower rate.C) Among the five languages in the table, the language that is spoken the fastest is also the language that conveys information the fastest.D) Serbian and Spanish are spoken at approximately the same rate, but Serbian conveys information faster than Spanish does.