Finding the Fourth Proportional to 1,724.32, 2,379.78 and 978.40

Step by Step Solution

1. Step 1: Write the proportion equation
   1,724.32 : 2,379.78 = 978.40 : x
2. Step 2: Convert to fraction form
   1,724.32/2,379.78 = 978.40/x
3. Step 3: Cross multiply
   1,724.32x = 2,379.78 × 978.40
4. Step 4: Simplify right side
   1,724.32x = 2,328,376.75
5. Step 5: Solve for x
   x = 2,328,376.75/1,724.32
6. Step 6: Final answer
   x = 1,350.32