Finding the Fourth Proportional to 1,288.99, 1,783.50 and 1,123.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,288.99 : 1,783.50 = 1,123.55 : x
2. Step 2: Convert to fraction form
   1,288.99/1,783.50 = 1,123.55/x
3. Step 3: Cross multiply
   1,288.99x = 1,783.50 × 1,123.55
4. Step 4: Simplify right side
   1,288.99x = 2,003,851.43
5. Step 5: Solve for x
   x = 2,003,851.43/1,288.99
6. Step 6: Final answer
   x = 1,554.59