Finding the Fourth Proportional to 2,012.61, 3,019.83 and 780.30

Step by Step Solution

1. Step 1: Write the proportion equation
   2,012.61 : 3,019.83 = 780.30 : x
2. Step 2: Convert to fraction form
   2,012.61/3,019.83 = 780.30/x
3. Step 3: Cross multiply
   2,012.61x = 3,019.83 × 780.30
4. Step 4: Simplify right side
   2,012.61x = 2,356,354.35
5. Step 5: Solve for x
   x = 2,356,354.35/2,012.61
6. Step 6: Final answer
   x = 1,170.80