Finding the Fourth Proportional to 100.17, 138.33 and 76.91

Step by Step Solution

1. Step 1: Write the proportion equation
   100.17 : 138.33 = 76.91 : x
2. Step 2: Convert to fraction form
   100.17/138.33 = 76.91/x
3. Step 3: Cross multiply
   100.17x = 138.33 × 76.91
4. Step 4: Simplify right side
   100.17x = 10,638.27
5. Step 5: Solve for x
   x = 10,638.27/100.17
6. Step 6: Final answer
   x = 106.20