Finding the Fourth Proportional to 78.86, 108.78 and 51.22

Step by Step Solution

1. Step 1: Write the proportion equation
   78.86 : 108.78 = 51.22 : x
2. Step 2: Convert to fraction form
   78.86/108.78 = 51.22/x
3. Step 3: Cross multiply
   78.86x = 108.78 × 51.22
4. Step 4: Simplify right side
   78.86x = 5,571.71
5. Step 5: Solve for x
   x = 5,571.71/78.86
6. Step 6: Final answer
   x = 70.65