Finding the Fourth Proportional to 10,111.20, 15,199.20 and 7,209.60

Step by Step Solution

1. Step 1: Write the proportion equation
   10,111.20 : 15,199.20 = 7,209.60 : x
2. Step 2: Convert to fraction form
   10,111.20/15,199.20 = 7,209.60/x
3. Step 3: Cross multiply
   10,111.20x = 15,199.20 × 7,209.60
4. Step 4: Simplify right side
   10,111.20x = 109,580,152.32
5. Step 5: Solve for x
   x = 109,580,152.32/10,111.20
6. Step 6: Final answer
   x = 10,837.50