Finding the Fourth Proportional to 69.91, 104.87 and 42.78

Step by Step Solution

1. Step 1: Write the proportion equation
   69.91 : 104.87 = 42.78 : x
2. Step 2: Convert to fraction form
   69.91/104.87 = 42.78/x
3. Step 3: Cross multiply
   69.91x = 104.87 × 42.78
4. Step 4: Simplify right side
   69.91x = 4,486.34
5. Step 5: Solve for x
   x = 4,486.34/69.91
6. Step 6: Final answer
   x = 64.17