Finding the Fourth Proportional to 100.31, 138.36 and 72.72

Step by Step Solution

1. Step 1: Write the proportion equation
   100.31 : 138.36 = 72.72 : x
2. Step 2: Convert to fraction form
   100.31/138.36 = 72.72/x
3. Step 3: Cross multiply
   100.31x = 138.36 × 72.72
4. Step 4: Simplify right side
   100.31x = 10,061.79
5. Step 5: Solve for x
   x = 10,061.79/100.31
6. Step 6: Final answer
   x = 100.30