Finding the Third Proportional to 90.30 and 138.82

Step by Step Solution

1. Step 1: Write the proportion equation
   90.30 : 138.82 = 138.82 : x
2. Step 2: Convert to fraction form
   90.30/138.82 = 138.82/x
3. Step 3: Cross multiply
   90.30x = 138.82 × 138.82
4. Step 4: Simplify right side
   90.30x = 19,271.08
5. Step 5: Solve for x
   x = 19,271.08/90.30
6. Step 6: Final answer
   x = 213.42