Finding the Fourth Proportional to 1,388.16, 1,915.61 and 798.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.16 : 1,915.61 = 798.80 : x
2. Step 2: Convert to fraction form
   1,388.16/1,915.61 = 798.80/x
3. Step 3: Cross multiply
   1,388.16x = 1,915.61 × 798.80
4. Step 4: Simplify right side
   1,388.16x = 1,530,175.70
5. Step 5: Solve for x
   x = 1,530,175.70/1,388.16
6. Step 6: Final answer
   x = 1,102.30