The respiratory rate per minute in newborns varies according to a distribution that is approximately Normal with mean 50 and standard deviation 5.
The proportion of observations from a standard Normal distribution that take values less than 1.15 is about
(a)
0.1251.
(b)
0.8531.
(c)
0.8749.
The answer is C, but I'm unsure how to do this on a TI-89 using the normalCDF function
To find the proportion of observations from a standard Normal distribution that take values less than 1.15 using the TI-89 calculator, you can use the `normalcdf` function. Here's how you can do it step by step:
1. Turn on your TI-89 calculator and press the "Apps" button.
2. Scroll through the list of applications and select "Finance."
3. In the Finance application menu, scroll and select "distr."
4. Within the "distr" menu, select "normalcdf."
5. You will be prompted to enter the lower bound, upper bound, mean, and standard deviation for the normal distribution.
- Enter `-1E99` (a very small negative number) as the lower bound.
- Enter `1.15` as the upper bound.
- Enter `0` as the mean since we are working with a standard Normal distribution.
- Enter `1` as the standard deviation since we are working with a standard Normal distribution.
6. After entering the values, press "Enter" to calculate the result.
7. The result should be displayed as the proportion of observations less than `1.15`.
The correct answer should be approximately `0.8749`, which matches option (c) in the given choices.