Finding the Fourth Proportional to 91.57, 136.99 and 78.76

Step by Step Solution

1. Step 1: Write the proportion equation
   91.57 : 136.99 = 78.76 : x
2. Step 2: Convert to fraction form
   91.57/136.99 = 78.76/x
3. Step 3: Cross multiply
   91.57x = 136.99 × 78.76
4. Step 4: Simplify right side
   91.57x = 10,789.33
5. Step 5: Solve for x
   x = 10,789.33/91.57
6. Step 6: Final answer
   x = 117.83