Finding the Fourth Proportional to 99.91, 137.72 and 71.84

Step by Step Solution

1. Step 1: Write the proportion equation
   99.91 : 137.72 = 71.84 : x
2. Step 2: Convert to fraction form
   99.91/137.72 = 71.84/x
3. Step 3: Cross multiply
   99.91x = 137.72 × 71.84
4. Step 4: Simplify right side
   99.91x = 9,892.76
5. Step 5: Solve for x
   x = 9,892.76/99.91
6. Step 6: Final answer
   x = 99.02