Finding the Fourth Proportional to 5,115.86, 7,059.98 and 2,991.57

Step by Step Solution

1. Step 1: Write the proportion equation
   5,115.86 : 7,059.98 = 2,991.57 : x
2. Step 2: Convert to fraction form
   5,115.86/7,059.98 = 2,991.57/x
3. Step 3: Cross multiply
   5,115.86x = 7,059.98 × 2,991.57
4. Step 4: Simplify right side
   5,115.86x = 21,120,409.41
5. Step 5: Solve for x
   x = 21,120,409.41/5,115.86
6. Step 6: Final answer
   x = 4,128.42