Finding the Fourth Proportional to 1,388.58, 1,917.09 and 1,256.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.58 : 1,917.09 = 1,256.50 : x
2. Step 2: Convert to fraction form
   1,388.58/1,917.09 = 1,256.50/x
3. Step 3: Cross multiply
   1,388.58x = 1,917.09 × 1,256.50
4. Step 4: Simplify right side
   1,388.58x = 2,408,823.59
5. Step 5: Solve for x
   x = 2,408,823.59/1,388.58
6. Step 6: Final answer
   x = 1,734.74