Finding the Fourth Proportional to 21,056.78, 31,591.32 and 7,910.12

Step by Step Solution

1. Step 1: Write the proportion equation
   21,056.78 : 31,591.32 = 7,910.12 : x
2. Step 2: Convert to fraction form
   21,056.78/31,591.32 = 7,910.12/x
3. Step 3: Cross multiply
   21,056.78x = 31,591.32 × 7,910.12
4. Step 4: Simplify right side
   21,056.78x = 249,891,132.16
5. Step 5: Solve for x
   x = 249,891,132.16/21,056.78
6. Step 6: Final answer
   x = 11,867.49