Finding the Fourth Proportional to 78.67, 117.42 and 67.17

Step by Step Solution

1. Step 1: Write the proportion equation
   78.67 : 117.42 = 67.17 : x
2. Step 2: Convert to fraction form
   78.67/117.42 = 67.17/x
3. Step 3: Cross multiply
   78.67x = 117.42 × 67.17
4. Step 4: Simplify right side
   78.67x = 7,887.10
5. Step 5: Solve for x
   x = 7,887.10/78.67
6. Step 6: Final answer
   x = 100.26