Finding the Fourth Proportional to 1,370.27, 1,890.98 and 780.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,370.27 : 1,890.98 = 780.80 : x
2. Step 2: Convert to fraction form
   1,370.27/1,890.98 = 780.80/x
3. Step 3: Cross multiply
   1,370.27x = 1,890.98 × 780.80
4. Step 4: Simplify right side
   1,370.27x = 1,476,463.83
5. Step 5: Solve for x
   x = 1,476,463.83/1,370.27
6. Step 6: Final answer
   x = 1,077.50