Finding the Fourth Proportional to 100.91, 139.25 and 57.23

Step by Step Solution

1. Step 1: Write the proportion equation
   100.91 : 139.25 = 57.23 : x
2. Step 2: Convert to fraction form
   100.91/139.25 = 57.23/x
3. Step 3: Cross multiply
   100.91x = 139.25 × 57.23
4. Step 4: Simplify right side
   100.91x = 7,970.03
5. Step 5: Solve for x
   x = 7,970.03/100.91
6. Step 6: Final answer
   x = 78.98