Finding the Fourth Proportional to 100.98, 139.36 and 57.31

Step by Step Solution

1. Step 1: Write the proportion equation
   100.98 : 139.36 = 57.31 : x
2. Step 2: Convert to fraction form
   100.98/139.36 = 57.31/x
3. Step 3: Cross multiply
   100.98x = 139.36 × 57.31
4. Step 4: Simplify right side
   100.98x = 7,986.78
5. Step 5: Solve for x
   x = 7,986.78/100.98
6. Step 6: Final answer
   x = 79.09