Finding the Fourth Proportional to 91.29, 136.67 and 78.47

Step by Step Solution

1. Step 1: Write the proportion equation
   91.29 : 136.67 = 78.47 : x
2. Step 2: Convert to fraction form
   91.29/136.67 = 78.47/x
3. Step 3: Cross multiply
   91.29x = 136.67 × 78.47
4. Step 4: Simplify right side
   91.29x = 10,723.42
5. Step 5: Solve for x
   x = 10,723.42/91.29
6. Step 6: Final answer
   x = 117.47