Finding the Fourth Proportional to 87.78, 131.69 and 42.18

Step by Step Solution

1. Step 1: Write the proportion equation
   87.78 : 131.69 = 42.18 : x
2. Step 2: Convert to fraction form
   87.78/131.69 = 42.18/x
3. Step 3: Cross multiply
   87.78x = 131.69 × 42.18
4. Step 4: Simplify right side
   87.78x = 5,554.68
5. Step 5: Solve for x
   x = 5,554.68/87.78
6. Step 6: Final answer
   x = 63.28