Finding the Fourth Proportional to 99.42, 136.98 and 78.77

Step by Step Solution

1. Step 1: Write the proportion equation
   99.42 : 136.98 = 78.77 : x
2. Step 2: Convert to fraction form
   99.42/136.98 = 78.77/x
3. Step 3: Cross multiply
   99.42x = 136.98 × 78.77
4. Step 4: Simplify right side
   99.42x = 10,789.23
5. Step 5: Solve for x
   x = 10,789.23/99.42
6. Step 6: Final answer
   x = 108.52