Finding the Fourth Proportional to 1,377.69, 1,901.45 and 780.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,377.69 : 1,901.45 = 780.21 : x
2. Step 2: Convert to fraction form
   1,377.69/1,901.45 = 780.21/x
3. Step 3: Cross multiply
   1,377.69x = 1,901.45 × 780.21
4. Step 4: Simplify right side
   1,377.69x = 1,483,536.46
5. Step 5: Solve for x
   x = 1,483,536.46/1,377.69
6. Step 6: Final answer
   x = 1,076.83