Finding the Fourth Proportional to 721,643.31, 995,870.41 and 390,499.25

Step by Step Solution

1. Step 1: Write the proportion equation
   721,643.31 : 995,870.41 = 390,499.25 : x
2. Step 2: Convert to fraction form
   721,643.31/995,870.41 = 390,499.25/x
3. Step 3: Cross multiply
   721,643.31x = 995,870.41 × 390,499.25
4. Step 4: Simplify right side
   721,643.31x = 388,886,642,246.59
5. Step 5: Solve for x
   x = 388,886,642,246.59/721,643.31
6. Step 6: Final answer
   x = 538,890.39