Finding the Fourth Proportional to 2,112.78, 3,167.82 and 813

Step by Step Solution

1. Step 1: Write the proportion equation
   2,112.78 : 3,167.82 = 813 : x
2. Step 2: Convert to fraction form
   2,112.78/3,167.82 = 813/x
3. Step 3: Cross multiply
   2,112.78x = 3,167.82 × 813
4. Step 4: Simplify right side
   2,112.78x = 2,575,437.66
5. Step 5: Solve for x
   x = 2,575,437.66/2,112.78
6. Step 6: Final answer
   x = 1,218.98