Finding the Fourth Proportional to 72.74, 100.38 and 39.99

Step by Step Solution

1. Step 1: Write the proportion equation
   72.74 : 100.38 = 39.99 : x
2. Step 2: Convert to fraction form
   72.74/100.38 = 39.99/x
3. Step 3: Cross multiply
   72.74x = 100.38 × 39.99
4. Step 4: Simplify right side
   72.74x = 4,014.61
5. Step 5: Solve for x
   x = 4,014.61/72.74
6. Step 6: Final answer
   x = 55.19