Finding the Fourth Proportional to 10,870.12, 14,999.72 and 8,637.40

Step by Step Solution

1. Step 1: Write the proportion equation
   10,870.12 : 14,999.72 = 8,637.40 : x
2. Step 2: Convert to fraction form
   10,870.12/14,999.72 = 8,637.40/x
3. Step 3: Cross multiply
   10,870.12x = 14,999.72 × 8,637.40
4. Step 4: Simplify right side
   10,870.12x = 129,558,581.53
5. Step 5: Solve for x
   x = 129,558,581.53/10,870.12
6. Step 6: Final answer
   x = 11,918.78