Finding the Third Proportional to 216,758 and 287,688

Step by Step Solution

1. Step 1: Write the proportion equation
   216,758 : 287,688 = 287,688 : x
2. Step 2: Convert to fraction form
   216,758/287,688 = 287,688/x
3. Step 3: Cross multiply
   216,758x = 287,688 × 287,688
4. Step 4: Simplify right side
   216,758x = 82,764,385,344
5. Step 5: Solve for x
   x = 82,764,385,344/216,758
6. Step 6: Final answer
   x = 381,828.52