Finding the Fourth Proportional to 1,370.08, 1,890.35 and 780.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,370.08 : 1,890.35 = 780.50 : x
2. Step 2: Convert to fraction form
   1,370.08/1,890.35 = 780.50/x
3. Step 3: Cross multiply
   1,370.08x = 1,890.35 × 780.50
4. Step 4: Simplify right side
   1,370.08x = 1,475,426.32
5. Step 5: Solve for x
   x = 1,475,426.32/1,370.08
6. Step 6: Final answer
   x = 1,076.89