Finding the Fourth Proportional to 78.15, 118.05 and 78.15

Step by Step Solution

1. Step 1: Write the proportion equation
   78.15 : 118.05 = 78.15 : x
2. Step 2: Convert to fraction form
   78.15/118.05 = 78.15/x
3. Step 3: Cross multiply
   78.15x = 118.05 × 78.15
4. Step 4: Simplify right side
   78.15x = 9,225.61
5. Step 5: Solve for x
   x = 9,225.61/78.15
6. Step 6: Final answer
   x = 118.05