Finding the Fourth Proportional to 20,897.31, 31,345.15 and 5,315.34

Step by Step Solution

1. Step 1: Write the proportion equation
   20,897.31 : 31,345.15 = 5,315.34 : x
2. Step 2: Convert to fraction form
   20,897.31/31,345.15 = 5,315.34/x
3. Step 3: Cross multiply
   20,897.31x = 31,345.15 × 5,315.34
4. Step 4: Simplify right side
   20,897.31x = 166,609,959.59
5. Step 5: Solve for x
   x = 166,609,959.59/20,897.31
6. Step 6: Final answer
   x = 7,972.80