Finding the Fourth Proportional to 100.58, 138.82 and 72.99

Step by Step Solution

1. Step 1: Write the proportion equation
   100.58 : 138.82 = 72.99 : x
2. Step 2: Convert to fraction form
   100.58/138.82 = 72.99/x
3. Step 3: Cross multiply
   100.58x = 138.82 × 72.99
4. Step 4: Simplify right side
   100.58x = 10,132.47
5. Step 5: Solve for x
   x = 10,132.47/100.58
6. Step 6: Final answer
   x = 100.74