Answer: 0.375
========================================================
Step-by-step explanation:
The portion from x = 0 to x = 5 has area 0.625, so 62.5% of the total area is accounted for. The remaining 100% - 62.5% = 37.5% of the total area must be in the remaining portion from x = 5 to x = 8. Convert 37.5% to decimal form to get the answer 0.375
-----------------
Another approach
We have two disjoint areas under a curve. The two areas must add to 1. Let A be the unknown area
So,
0.625+A = 1
A = 1-0.625
A = 0.375
The area under the curve from x = 5 to x = 8 is 0.375