Finding the Fourth Proportional to 10,907.76, 15,066.78 and 8,420.61

Step by Step Solution

1. Step 1: Write the proportion equation
   10,907.76 : 15,066.78 = 8,420.61 : x
2. Step 2: Convert to fraction form
   10,907.76/15,066.78 = 8,420.61/x
3. Step 3: Cross multiply
   10,907.76x = 15,066.78 × 8,420.61
4. Step 4: Simplify right side
   10,907.76x = 126,871,478.34
5. Step 5: Solve for x
   x = 126,871,478.34/10,907.76
6. Step 6: Final answer
   x = 11,631.30