Finding the Fourth Proportional to 1,005.99, 1,388.23 and 557.84

Step by Step Solution

1. Step 1: Write the proportion equation
   1,005.99 : 1,388.23 = 557.84 : x
2. Step 2: Convert to fraction form
   1,005.99/1,388.23 = 557.84/x
3. Step 3: Cross multiply
   1,005.99x = 1,388.23 × 557.84
4. Step 4: Simplify right side
   1,005.99x = 774,410.22
5. Step 5: Solve for x
   x = 774,410.22/1,005.99
6. Step 6: Final answer
   x = 769.80