Finding the Fourth Proportional to 12,391.05, 17,101.53 and 7,917.78

Step by Step Solution

1. Step 1: Write the proportion equation
   12,391.05 : 17,101.53 = 7,917.78 : x
2. Step 2: Convert to fraction form
   12,391.05/17,101.53 = 7,917.78/x
3. Step 3: Cross multiply
   12,391.05x = 17,101.53 × 7,917.78
4. Step 4: Simplify right side
   12,391.05x = 135,406,152.20
5. Step 5: Solve for x
   x = 135,406,152.20/12,391.05
6. Step 6: Final answer
   x = 10,927.74