Finding the Fourth Proportional to 87.72, 131.54 and 42.09

Step by Step Solution

1. Step 1: Write the proportion equation
   87.72 : 131.54 = 42.09 : x
2. Step 2: Convert to fraction form
   87.72/131.54 = 42.09/x
3. Step 3: Cross multiply
   87.72x = 131.54 × 42.09
4. Step 4: Simplify right side
   87.72x = 5,536.52
5. Step 5: Solve for x
   x = 5,536.52/87.72
6. Step 6: Final answer
   x = 63.12