Finding the Fourth Proportional to 1,378.18, 1,902.12 and 788.70

Step by Step Solution

1. Step 1: Write the proportion equation
   1,378.18 : 1,902.12 = 788.70 : x
2. Step 2: Convert to fraction form
   1,378.18/1,902.12 = 788.70/x
3. Step 3: Cross multiply
   1,378.18x = 1,902.12 × 788.70
4. Step 4: Simplify right side
   1,378.18x = 1,500,202.04
5. Step 5: Solve for x
   x = 1,500,202.04/1,378.18
6. Step 6: Final answer
   x = 1,088.54