Finding the Fourth Proportional to 27,978.72, 38,612.64 and 15,715.12

Step by Step Solution

1. Step 1: Write the proportion equation
   27,978.72 : 38,612.64 = 15,715.12 : x
2. Step 2: Convert to fraction form
   27,978.72/38,612.64 = 15,715.12/x
3. Step 3: Cross multiply
   27,978.72x = 38,612.64 × 15,715.12
4. Step 4: Simplify right side
   27,978.72x = 606,802,141.12
5. Step 5: Solve for x
   x = 606,802,141.12/27,978.72
6. Step 6: Final answer
   x = 21,687.99