Finding the Fourth Proportional to 1,978.69, 2,729.74 and 1,389.61

Step by Step Solution

1. Step 1: Write the proportion equation
   1,978.69 : 2,729.74 = 1,389.61 : x
2. Step 2: Convert to fraction form
   1,978.69/2,729.74 = 1,389.61/x
3. Step 3: Cross multiply
   1,978.69x = 2,729.74 × 1,389.61
4. Step 4: Simplify right side
   1,978.69x = 3,793,274.00
5. Step 5: Solve for x
   x = 3,793,274.00/1,978.69
6. Step 6: Final answer
   x = 1,917.06