Finding the Fourth Proportional to 1,401.50, 1,934.20 and 780.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,401.50 : 1,934.20 = 780.50 : x
2. Step 2: Convert to fraction form
   1,401.50/1,934.20 = 780.50/x
3. Step 3: Cross multiply
   1,401.50x = 1,934.20 × 780.50
4. Step 4: Simplify right side
   1,401.50x = 1,509,643.10
5. Step 5: Solve for x
   x = 1,509,643.10/1,401.50
6. Step 6: Final answer
   x = 1,077.16