Finding the Fourth Proportional to 100.72, 138.89 and 76.22

Step by Step Solution

1. Step 1: Write the proportion equation
   100.72 : 138.89 = 76.22 : x
2. Step 2: Convert to fraction form
   100.72/138.89 = 76.22/x
3. Step 3: Cross multiply
   100.72x = 138.89 × 76.22
4. Step 4: Simplify right side
   100.72x = 10,585.69
5. Step 5: Solve for x
   x = 10,585.69/100.72
6. Step 6: Final answer
   x = 105.10