Finding the Fourth Proportional to 1,347.80, 1,859.30 and 780.59

Step by Step Solution

1. Step 1: Write the proportion equation
   1,347.80 : 1,859.30 = 780.59 : x
2. Step 2: Convert to fraction form
   1,347.80/1,859.30 = 780.59/x
3. Step 3: Cross multiply
   1,347.80x = 1,859.30 × 780.59
4. Step 4: Simplify right side
   1,347.80x = 1,451,337.79
5. Step 5: Solve for x
   x = 1,451,337.79/1,347.80
6. Step 6: Final answer
   x = 1,076.82