Finding the Fourth Proportional to 1,389.77, 1,917.90 and 760.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.77 : 1,917.90 = 760.21 : x
2. Step 2: Convert to fraction form
   1,389.77/1,917.90 = 760.21/x
3. Step 3: Cross multiply
   1,389.77x = 1,917.90 × 760.21
4. Step 4: Simplify right side
   1,389.77x = 1,458,004.69
5. Step 5: Solve for x
   x = 1,458,004.69/1,389.77
6. Step 6: Final answer
   x = 1,049.10