Finding the Fourth Proportional to 113.69, 156.76 and 76.78

Step by Step Solution

1. Step 1: Write the proportion equation
   113.69 : 156.76 = 76.78 : x
2. Step 2: Convert to fraction form
   113.69/156.76 = 76.78/x
3. Step 3: Cross multiply
   113.69x = 156.76 × 76.78
4. Step 4: Simplify right side
   113.69x = 12,036.25
5. Step 5: Solve for x
   x = 12,036.25/113.69
6. Step 6: Final answer
   x = 105.87