Finding the Third Proportional to 31,720 and 69,090

Step by Step Solution

1. Step 1: Write the proportion equation
   31,720 : 69,090 = 69,090 : x
2. Step 2: Convert to fraction form
   31,720/69,090 = 69,090/x
3. Step 3: Cross multiply
   31,720x = 69,090 × 69,090
4. Step 4: Simplify right side
   31,720x = 4,773,428,100
5. Step 5: Solve for x
   x = 4,773,428,100/31,720
6. Step 6: Final answer
   x = 150,486.38