Finding the Fourth Proportional to 99.91, 149.78 and 39.09

Step by Step Solution

1. Step 1: Write the proportion equation
   99.91 : 149.78 = 39.09 : x
2. Step 2: Convert to fraction form
   99.91/149.78 = 39.09/x
3. Step 3: Cross multiply
   99.91x = 149.78 × 39.09
4. Step 4: Simplify right side
   99.91x = 5,854.15
5. Step 5: Solve for x
   x = 5,854.15/99.91
6. Step 6: Final answer
   x = 58.60