Finding the Fourth Proportional to 1,288.74, 1,783.15 and 1,123.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,288.74 : 1,783.15 = 1,123.30 : x
2. Step 2: Convert to fraction form
   1,288.74/1,783.15 = 1,123.30/x
3. Step 3: Cross multiply
   1,288.74x = 1,783.15 × 1,123.30
4. Step 4: Simplify right side
   1,288.74x = 2,003,005.13
5. Step 5: Solve for x
   x = 2,003,005.13/1,288.74
6. Step 6: Final answer
   x = 1,554.24