Finding the Fourth Proportional to 1,378.32, 1,902.56 and 1,007.20

Step by Step Solution

1. Step 1: Write the proportion equation
   1,378.32 : 1,902.56 = 1,007.20 : x
2. Step 2: Convert to fraction form
   1,378.32/1,902.56 = 1,007.20/x
3. Step 3: Cross multiply
   1,378.32x = 1,902.56 × 1,007.20
4. Step 4: Simplify right side
   1,378.32x = 1,916,255.77
5. Step 5: Solve for x
   x = 1,916,255.77/1,378.32
6. Step 6: Final answer
   x = 1,390.29