Finding the Fourth Proportional to 91.78, 137.56 and 42.97

Step by Step Solution

1. Step 1: Write the proportion equation
   91.78 : 137.56 = 42.97 : x
2. Step 2: Convert to fraction form
   91.78/137.56 = 42.97/x
3. Step 3: Cross multiply
   91.78x = 137.56 × 42.97
4. Step 4: Simplify right side
   91.78x = 5,910.05
5. Step 5: Solve for x
   x = 5,910.05/91.78
6. Step 6: Final answer
   x = 64.39