Finding the Third Proportional to 780.50 and 1,131

Step by Step Solution

1. Step 1: Write the proportion equation
   780.50 : 1,131 = 1,131 : x
2. Step 2: Convert to fraction form
   780.50/1,131 = 1,131/x
3. Step 3: Cross multiply
   780.50x = 1,131 × 1,131
4. Step 4: Simplify right side
   780.50x = 1,279,161
5. Step 5: Solve for x
   x = 1,279,161/780.50
6. Step 6: Final answer
   x = 1,638.90