Finding the Fourth Proportional to 78.10, 117.18 and 51.05

Step by Step Solution

1. Step 1: Write the proportion equation
   78.10 : 117.18 = 51.05 : x
2. Step 2: Convert to fraction form
   78.10/117.18 = 51.05/x
3. Step 3: Cross multiply
   78.10x = 117.18 × 51.05
4. Step 4: Simplify right side
   78.10x = 5,982.33
5. Step 5: Solve for x
   x = 5,982.33/78.10
6. Step 6: Final answer
   x = 76.60