Finding the Fourth Proportional to 1,378.26, 1,901.88 and 780.75

Step by Step Solution

1. Step 1: Write the proportion equation
   1,378.26 : 1,901.88 = 780.75 : x
2. Step 2: Convert to fraction form
   1,378.26/1,901.88 = 780.75/x
3. Step 3: Cross multiply
   1,378.26x = 1,901.88 × 780.75
4. Step 4: Simplify right side
   1,378.26x = 1,484,892.81
5. Step 5: Solve for x
   x = 1,484,892.81/1,378.26
6. Step 6: Final answer
   x = 1,077.37