Use this information to estimate the mean number of years worked in education for all high school teachers in the community by calculating a 99% confidence interval. In her sample, the average number of years was 14.2 with a standard deviation of 6.8. Using a t-interval on the calculator has almost the same steps as using a z-interval, as you will see below.įor a statistics project, a student samples 37 high school teachers in her community and records how many years they have worked in education. When the population standard deviation is unknown, we will use a t-interval to estimate the mean. Note – there are many other ways to write this interval. This means that we are 95% confident that the true mean time that college students spend browsing the internet each day is between 62.15 minutes and 71.85 minutes. Here we are given our 95% confidence interval as (62.149, 71.851). It is very easy to misunderstand what they truly mean! Highlight CALCULATE and then press ENTER to get your interval.
#Using graphing calculator ti 84 online how to
Please make sure to read the explanation of how to interpret intervals in general. Notice that the calculator asks for sigma (the population standard deviation) – this should help you remember that you shouldn’t be using this unless you have sigma already. This is really only useful for small data sets. If you had a list of data instead, you could enter it into L1 and then use DATA. Since we have statistics for the sample already calculated, we will highlight STATS at the top. Step 1: Go to the z-interval on the calculator. Therefore, a z-interval can be used to calculate the confidence interval. In this example, we are told that the population standard deviation is thought to be 14 minutes and we have a large enough sample size. If it is believed that the population standard deviation is 14 minutes, then calculate a 95% confidence interval to estimate the average time spent by college students browsing the internet each day. In a sample of 32 college students, the average time spent browsing the internet each day was about 67 minutes. Note: You can scroll down to see a video of these steps! z-IntervalsĪ psychologist wants to estimate the amount of time college students spend browsing the internet each day. In this article, we will see how to use the TI83/84 calculator to calculate z and t intervals. In both cases, you can either use the formula to compute the interval by hand or use a graphing calculator (or other software).
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