Questions: Find the area under the standard normal curve to the left of z=1.25. A. 0.1056 B. 0.2318 C. 0.8944 D. 0.7682

Transcript text: Find the area under the standard normal curve to the left of $z=1.25$. A. 0.1056 B. 0.2318 C. 0.8944 D. 0.7682

Solution

Solution Steps

Step 1: Define the Problem

We need to find the area under the standard normal curve to the left of $ z = 1.25 $. This area corresponds to the cumulative distribution function (CDF) of the standard normal distribution, denoted as $ \Phi(z) $.

Step 2: Calculate the CDF

The area to the left of $ z = 1.25 $ can be expressed mathematically as: \[ P(Z \leq 1.25) = \Phi(1.25) - \Phi(-\infty) \] Since $ \Phi(-\infty) = 0 $, we simplify this to: \[ P(Z \leq 1.25) = \Phi(1.25) \]

Step 3: Find the Value of $ \Phi(1.25) $

From the calculations, we find: \[ \Phi(1.25) = 0.8944 \]