Finding the Fourth Proportional to 1,312.25, 1,810.78 and 839.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,312.25 : 1,810.78 = 839.31 : x
2. Step 2: Convert to fraction form
   1,312.25/1,810.78 = 839.31/x
3. Step 3: Cross multiply
   1,312.25x = 1,810.78 × 839.31
4. Step 4: Simplify right side
   1,312.25x = 1,519,796.87
5. Step 5: Solve for x
   x = 1,519,796.87/1,312.25
6. Step 6: Final answer
   x = 1,158.17