Finding the Third Proportional to 262,642.50 and 390,136.50

Step by Step Solution

1. Step 1: Write the proportion equation
   262,642.50 : 390,136.50 = 390,136.50 : x
2. Step 2: Convert to fraction form
   262,642.50/390,136.50 = 390,136.50/x
3. Step 3: Cross multiply
   262,642.50x = 390,136.50 × 390,136.50
4. Step 4: Simplify right side
   262,642.50x = 152,206,488,632.25
5. Step 5: Solve for x
   x = 152,206,488,632.25/262,642.50
6. Step 6: Final answer
   x = 579,519.65