Finding the Fourth Proportional to 1,386.80, 1,913.91 and 797.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,386.80 : 1,913.91 = 797.31 : x
2. Step 2: Convert to fraction form
   1,386.80/1,913.91 = 797.31/x
3. Step 3: Cross multiply
   1,386.80x = 1,913.91 × 797.31
4. Step 4: Simplify right side
   1,386.80x = 1,525,979.58
5. Step 5: Solve for x
   x = 1,525,979.58/1,386.80
6. Step 6: Final answer
   x = 1,100.36