# My notes are not clear Pt 2

1. Jun 23, 2014

### billbennett770

1. The problem statement, all variables and given/known data

It has been suggested that reaction time to brake a signal from standard brake ligths can be modeled with a normal distribution having a mean of 1.25 seconds and a standard deviation of .46 seconds. What is the probability that the reaction time is between 1. and 1.75. Use your calculator to find the probability.

2. Relevant equations
P(a-μ)/σ ≤ z ≤ (b-μ)/σ

3. The attempt at a solution
(1-1.25)/.46 ≤ z ≤ (1.75-1.25)/.46

-.5434782609 ≤ z ≤ 1.086956533

I did this part because my notes from my teacher do not tell me how to do this on the calculator. however, I tried in the Z-test section, with my input section on stats. I know where to plug the μ and the σ, but not the 1 and 1.75. x (with a line above it), and a n.

2. Jun 23, 2014

### Simon Bridge

The 1 and the 1.75 are the limits of the integration - do you know the equation for a Normal distribution?

You can also work it out using the properties of the normal distribution - and known values for the unit normal - do you have access to tables? Your calculator may have such a table built in - but I don't know what kind you have.