Finding the Fourth Proportional to 61.31, 83.81 and 61.31

Step by Step Solution

1. Step 1: Write the proportion equation
   61.31 : 83.81 = 61.31 : x
2. Step 2: Convert to fraction form
   61.31/83.81 = 61.31/x
3. Step 3: Cross multiply
   61.31x = 83.81 × 61.31
4. Step 4: Simplify right side
   61.31x = 5,138.11
5. Step 5: Solve for x
   x = 5,138.11/61.31
6. Step 6: Final answer
   x = 83.81