Finding the Fourth Proportional to 1,408.78, 1,943.40 and 988.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,408.78 : 1,943.40 = 988.30 : x
2. Step 2: Convert to fraction form
   1,408.78/1,943.40 = 988.30/x
3. Step 3: Cross multiply
   1,408.78x = 1,943.40 × 988.30
4. Step 4: Simplify right side
   1,408.78x = 1,920,662.22
5. Step 5: Solve for x
   x = 1,920,662.22/1,408.78
6. Step 6: Final answer
   x = 1,363.35