Finding the Fourth Proportional to 1,421.78, 1,962.06 and 800.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,421.78 : 1,962.06 = 800.78 : x
2. Step 2: Convert to fraction form
   1,421.78/1,962.06 = 800.78/x
3. Step 3: Cross multiply
   1,421.78x = 1,962.06 × 800.78
4. Step 4: Simplify right side
   1,421.78x = 1,571,178.41
5. Step 5: Solve for x
   x = 1,571,178.41/1,421.78
6. Step 6: Final answer
   x = 1,105.08