Finding the Third Proportional to 58.31 and 90.31

Step by Step Solution

1. Step 1: Write the proportion equation
   58.31 : 90.31 = 90.31 : x
2. Step 2: Convert to fraction form
   58.31/90.31 = 90.31/x
3. Step 3: Cross multiply
   58.31x = 90.31 × 90.31
4. Step 4: Simplify right side
   58.31x = 8,156.35
5. Step 5: Solve for x
   x = 8,156.35/58.31
6. Step 6: Final answer
   x = 139.87