Finding the Fourth Proportional to 99.15, 136.89 and 78.53

Step by Step Solution

1. Step 1: Write the proportion equation
   99.15 : 136.89 = 78.53 : x
2. Step 2: Convert to fraction form
   99.15/136.89 = 78.53/x
3. Step 3: Cross multiply
   99.15x = 136.89 × 78.53
4. Step 4: Simplify right side
   99.15x = 10,749.29
5. Step 5: Solve for x
   x = 10,749.29/99.15
6. Step 6: Final answer
   x = 108.42