Finding the Fourth Proportional to 1,391.21, 1,919.89 and 761.73

Step by Step Solution

1. Step 1: Write the proportion equation
   1,391.21 : 1,919.89 = 761.73 : x
2. Step 2: Convert to fraction form
   1,391.21/1,919.89 = 761.73/x
3. Step 3: Cross multiply
   1,391.21x = 1,919.89 × 761.73
4. Step 4: Simplify right side
   1,391.21x = 1,462,439.10
5. Step 5: Solve for x
   x = 1,462,439.10/1,391.21
6. Step 6: Final answer
   x = 1,051.20