Finding the Third Proportional to 187.31 and 289.78

Step by Step Solution

1. Step 1: Write the proportion equation
   187.31 : 289.78 = 289.78 : x
2. Step 2: Convert to fraction form
   187.31/289.78 = 289.78/x
3. Step 3: Cross multiply
   187.31x = 289.78 × 289.78
4. Step 4: Simplify right side
   187.31x = 83,973.17
5. Step 5: Solve for x
   x = 83,973.17/187.31
6. Step 6: Final answer
   x = 448.31