Finding the Fourth Proportional to 100.89, 139.23 and 56.63

Step by Step Solution

1. Step 1: Write the proportion equation
   100.89 : 139.23 = 56.63 : x
2. Step 2: Convert to fraction form
   100.89/139.23 = 56.63/x
3. Step 3: Cross multiply
   100.89x = 139.23 × 56.63
4. Step 4: Simplify right side
   100.89x = 7,884.59
5. Step 5: Solve for x
   x = 7,884.59/100.89
6. Step 6: Final answer
   x = 78.15