Finding the Fourth Proportional to 1,724.79, 2,380.20 and 978.70

Step by Step Solution

1. Step 1: Write the proportion equation
   1,724.79 : 2,380.20 = 978.70 : x
2. Step 2: Convert to fraction form
   1,724.79/2,380.20 = 978.70/x
3. Step 3: Cross multiply
   1,724.79x = 2,380.20 × 978.70
4. Step 4: Simplify right side
   1,724.79x = 2,329,501.74
5. Step 5: Solve for x
   x = 2,329,501.74/1,724.79
6. Step 6: Final answer
   x = 1,350.60