Finding the Fourth Proportional to 1,398.41, 1,928.38 and 978.63

Step by Step Solution

1. Step 1: Write the proportion equation
   1,398.41 : 1,928.38 = 978.63 : x
2. Step 2: Convert to fraction form
   1,398.41/1,928.38 = 978.63/x
3. Step 3: Cross multiply
   1,398.41x = 1,928.38 × 978.63
4. Step 4: Simplify right side
   1,398.41x = 1,887,176.28
5. Step 5: Solve for x
   x = 1,887,176.28/1,398.41
6. Step 6: Final answer
   x = 1,349.51