Finding the Fourth Proportional to 78.69, 108.53 and 54.18

Step by Step Solution

1. Step 1: Write the proportion equation
   78.69 : 108.53 = 54.18 : x
2. Step 2: Convert to fraction form
   78.69/108.53 = 54.18/x
3. Step 3: Cross multiply
   78.69x = 108.53 × 54.18
4. Step 4: Simplify right side
   78.69x = 5,880.43
5. Step 5: Solve for x
   x = 5,880.43/78.69
6. Step 6: Final answer
   x = 74.73