Finding the Fourth Proportional to 1,088.78, 1,501.50 and 839.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,088.78 : 1,501.50 = 839.71 : x
2. Step 2: Convert to fraction form
   1,088.78/1,501.50 = 839.71/x
3. Step 3: Cross multiply
   1,088.78x = 1,501.50 × 839.71
4. Step 4: Simplify right side
   1,088.78x = 1,260,824.57
5. Step 5: Solve for x
   x = 1,260,824.57/1,088.78
6. Step 6: Final answer
   x = 1,158.02