Finding the Fourth Proportional to 1,378.30, 1,901.78 and 788.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,378.30 : 1,901.78 = 788.71 : x
2. Step 2: Convert to fraction form
   1,378.30/1,901.78 = 788.71/x
3. Step 3: Cross multiply
   1,378.30x = 1,901.78 × 788.71
4. Step 4: Simplify right side
   1,378.30x = 1,499,952.90
5. Step 5: Solve for x
   x = 1,499,952.90/1,378.30
6. Step 6: Final answer
   x = 1,088.26