Finding the Fourth Proportional to 78.42, 117.68 and 72.30

Step by Step Solution

1. Step 1: Write the proportion equation
   78.42 : 117.68 = 72.30 : x
2. Step 2: Convert to fraction form
   78.42/117.68 = 72.30/x
3. Step 3: Cross multiply
   78.42x = 117.68 × 72.30
4. Step 4: Simplify right side
   78.42x = 8,507.90
5. Step 5: Solve for x
   x = 8,507.90/78.42
6. Step 6: Final answer
   x = 108.49