Finding the Fourth Proportional to 78.75, 108.69 and 51.15

Step by Step Solution

1. Step 1: Write the proportion equation
   78.75 : 108.69 = 51.15 : x
2. Step 2: Convert to fraction form
   78.75/108.69 = 51.15/x
3. Step 3: Cross multiply
   78.75x = 108.69 × 51.15
4. Step 4: Simplify right side
   78.75x = 5,559.49
5. Step 5: Solve for x
   x = 5,559.49/78.75
6. Step 6: Final answer
   x = 70.60