The weights of male babies less than 2 months old in the United States is normally distributed with a mean of 11.5 pounds and a standard deviation of 2.7 pounds.

Find the 80th percentile score for these weights.

I don't have a table, I have to figure it out using the TI-84 calculator and I don't know where to go with that.

Don't have a TI-84 calculator, but....

Z = (score-mean)/SD

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability (.80) related to a Z score. Insert that value into the above equation to find the score.

To find the 80th percentile score for the weights of male babies less than 2 months old, you can use the TI-84 calculator.

Step 1: Open the calculator and navigate to the "DISTR" menu. This can usually be found by pressing the "2ND" key followed by the "VARS" key (which is the "DISTR" key).

Step 2: In the "DISTR" menu, scroll down or use the arrow keys to highlight the "invNorm(" function and press the "ENTER" key.

Step 3: You will see the syntax for the "invNorm(" function appear on the screen. The syntax should look like: invNorm(area to the left, mean, standard deviation).

Step 4: Replace the values in the syntax to match the information given in the problem. The "area to the left" is determined by subtracting the desired percentile from 1. In this case, since you're looking for the 80th percentile, the area to the left is 1 - 0.80 = 0.20. So, the syntax for the "invNorm(" function becomes: invNorm(0.20, 11.5, 2.7).

Step 5: After entering the modified syntax, press the "ENTER" key. The calculator will then calculate the value corresponding to the 80th percentile score for the weights.

The calculator should display the value of the 80th percentile score for the weights of male babies less than 2 months old.