Finding the Fourth Proportional to 100.28, 138.23 and 76.89

Step by Step Solution

1. Step 1: Write the proportion equation
   100.28 : 138.23 = 76.89 : x
2. Step 2: Convert to fraction form
   100.28/138.23 = 76.89/x
3. Step 3: Cross multiply
   100.28x = 138.23 × 76.89
4. Step 4: Simplify right side
   100.28x = 10,628.50
5. Step 5: Solve for x
   x = 10,628.50/100.28
6. Step 6: Final answer
   x = 105.99