Finding the Fourth Proportional to 78.94, 108.96 and 64.42

Step by Step Solution

1. Step 1: Write the proportion equation
   78.94 : 108.96 = 64.42 : x
2. Step 2: Convert to fraction form
   78.94/108.96 = 64.42/x
3. Step 3: Cross multiply
   78.94x = 108.96 × 64.42
4. Step 4: Simplify right side
   78.94x = 7,019.20
5. Step 5: Solve for x
   x = 7,019.20/78.94
6. Step 6: Final answer
   x = 88.92