Finding the Fourth Proportional to 28,650.96, 42,978.96 and 8,931.60

Step by Step Solution

1. Step 1: Write the proportion equation
   28,650.96 : 42,978.96 = 8,931.60 : x
2. Step 2: Convert to fraction form
   28,650.96/42,978.96 = 8,931.60/x
3. Step 3: Cross multiply
   28,650.96x = 42,978.96 × 8,931.60
4. Step 4: Simplify right side
   28,650.96x = 383,870,879.14
5. Step 5: Solve for x
   x = 383,870,879.14/28,650.96
6. Step 6: Final answer
   x = 13,398.19