Finding the Fourth Proportional to 402,978.68, 556,088.61 and 221,661.34

Step by Step Solution

1. Step 1: Write the proportion equation
   402,978.68 : 556,088.61 = 221,661.34 : x
2. Step 2: Convert to fraction form
   402,978.68/556,088.61 = 221,661.34/x
3. Step 3: Cross multiply
   402,978.68x = 556,088.61 × 221,661.34
4. Step 4: Simplify right side
   402,978.68x = 123,263,343,670.89
5. Step 5: Solve for x
   x = 123,263,343,670.89/402,978.68
6. Step 6: Final answer
   x = 305,880.56