Which of the following properties is NOT true for a standard normal curve?

The property that is not true for a standard normal curve is that it has a finite extent. A standard normal curve, like any normal distribution, has a theoretical nature that allows it to extend infinitely in both directions along the horizontal axis. This characteristic is essential because it reflects the concept that in a normal distribution, every value is possible, even though the probability for extreme values decreases significantly.

The total area under the curve being equal to 1 is a defining property of probability distributions, indicating that the total probability across all potential outcomes must add up to one. The symmetry about the mean also holds true, as the standard normal curve is centered at zero with tails that are perfectly mirrored. Lastly, the curve extending infinitely in both directions is directly related to the characteristics of the normal distribution, emphasizing that while values can get very small in probability, they are never completely ruled out.