Finding the Fourth Proportional to 91.03, 136.56 and 78.72

Step by Step Solution

1. Step 1: Write the proportion equation
   91.03 : 136.56 = 78.72 : x
2. Step 2: Convert to fraction form
   91.03/136.56 = 78.72/x
3. Step 3: Cross multiply
   91.03x = 136.56 × 78.72
4. Step 4: Simplify right side
   91.03x = 10,749.61
5. Step 5: Solve for x
   x = 10,749.61/91.03
6. Step 6: Final answer
   x = 118.09