Finding the Fourth Proportional to 5,290.83, 7,918.56 and 5,220.90

Step by Step Solution

1. Step 1: Write the proportion equation
   5,290.83 : 7,918.56 = 5,220.90 : x
2. Step 2: Convert to fraction form
   5,290.83/7,918.56 = 5,220.90/x
3. Step 3: Cross multiply
   5,290.83x = 7,918.56 × 5,220.90
4. Step 4: Simplify right side
   5,290.83x = 41,342,009.90
5. Step 5: Solve for x
   x = 41,342,009.90/5,290.83
6. Step 6: Final answer
   x = 7,813.90