Finding the Fourth Proportional to 1,370.25, 1,890.61 and 780.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,370.25 : 1,890.61 = 780.57 : x
2. Step 2: Convert to fraction form
   1,370.25/1,890.61 = 780.57/x
3. Step 3: Cross multiply
   1,370.25x = 1,890.61 × 780.57
4. Step 4: Simplify right side
   1,370.25x = 1,475,751.50
5. Step 5: Solve for x
   x = 1,475,751.50/1,370.25
6. Step 6: Final answer
   x = 1,076.99