Finding the Third Proportional to 521 and 1,284.50

Step by Step Solution

1. Step 1: Write the proportion equation
   521 : 1,284.50 = 1,284.50 : x
2. Step 2: Convert to fraction form
   521/1,284.50 = 1,284.50/x
3. Step 3: Cross multiply
   521x = 1,284.50 × 1,284.50
4. Step 4: Simplify right side
   521x = 1,649,940.25
5. Step 5: Solve for x
   x = 1,649,940.25/521
6. Step 6: Final answer
   x = 3,166.87