Finding the Fourth Proportional to 65,665.87, 91,230.70 and 64,878.55

Step by Step Solution

1. Step 1: Write the proportion equation
   65,665.87 : 91,230.70 = 64,878.55 : x
2. Step 2: Convert to fraction form
   65,665.87/91,230.70 = 64,878.55/x
3. Step 3: Cross multiply
   65,665.87x = 91,230.70 × 64,878.55
4. Step 4: Simplify right side
   65,665.87x = 5,918,915,531.49
5. Step 5: Solve for x
   x = 5,918,915,531.49/65,665.87
6. Step 6: Final answer
   x = 90,136.86