Finding the Fourth Proportional to 100.64, 139.01 and 72.96

Step by Step Solution

1. Step 1: Write the proportion equation
   100.64 : 139.01 = 72.96 : x
2. Step 2: Convert to fraction form
   100.64/139.01 = 72.96/x
3. Step 3: Cross multiply
   100.64x = 139.01 × 72.96
4. Step 4: Simplify right side
   100.64x = 10,142.17
5. Step 5: Solve for x
   x = 10,142.17/100.64
6. Step 6: Final answer
   x = 100.78