Finding the Third Proportional to 815.63 and 1,780.50

Step by Step Solution

1. Step 1: Write the proportion equation
   815.63 : 1,780.50 = 1,780.50 : x
2. Step 2: Convert to fraction form
   815.63/1,780.50 = 1,780.50/x
3. Step 3: Cross multiply
   815.63x = 1,780.50 × 1,780.50
4. Step 4: Simplify right side
   815.63x = 3,170,180.25
5. Step 5: Solve for x
   x = 3,170,180.25/815.63
6. Step 6: Final answer
   x = 3,886.81