The area under a complete density curve is equal to 1. So, the percent of the total area under a portion of the curve is equal to the area under that part of the curve.

We are looking for the area under the density curve when x < 1.

We can use the area formula for a triangle to find this area:

Area = \frac{1}{2} \times base \times height = \frac{1}{2} \times 1 \times 0.1 = 0.05

**So the percent of the area under the density curve where x \lt 1 is 5%.**

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**Density Curves** (video) | Khan Academy

An introduction to **density curves** for visualizing **distributions**. ... Imagine that you
have a continuous **data** set (like the quantity of water that ... I understand that the
**area under** the **curve** is the probability of getting an X in that interval. ... **AP**® is a
registered trademark of the College Board, which has not reviewed this resource.

For more information, see **Density Curves** (video) | Khan Academy