Finding the Fourth Proportional to 1,388.64, 1,914.48 and 1,038.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.64 : 1,914.48 = 1,038.72 : x
2. Step 2: Convert to fraction form
   1,388.64/1,914.48 = 1,038.72/x
3. Step 3: Cross multiply
   1,388.64x = 1,914.48 × 1,038.72
4. Step 4: Simplify right side
   1,388.64x = 1,988,608.67
5. Step 5: Solve for x
   x = 1,988,608.67/1,388.64
6. Step 6: Final answer
   x = 1,432.05