Finding the Third Proportional to 291.50 and 641.38

Step by Step Solution

1. Step 1: Write the proportion equation
   291.50 : 641.38 = 641.38 : x
2. Step 2: Convert to fraction form
   291.50/641.38 = 641.38/x
3. Step 3: Cross multiply
   291.50x = 641.38 × 641.38
4. Step 4: Simplify right side
   291.50x = 411,361.89
5. Step 5: Solve for x
   x = 411,361.89/291.50
6. Step 6: Final answer
   x = 1,411.19