Finding the Fourth Proportional to 90.58, 136.22 and 78.63

Step by Step Solution

1. Step 1: Write the proportion equation
   90.58 : 136.22 = 78.63 : x
2. Step 2: Convert to fraction form
   90.58/136.22 = 78.63/x
3. Step 3: Cross multiply
   90.58x = 136.22 × 78.63
4. Step 4: Simplify right side
   90.58x = 10,710.98
5. Step 5: Solve for x
   x = 10,710.98/90.58
6. Step 6: Final answer
   x = 118.25