Finding the Fourth Proportional to 9,987.08, 13,780.56 and 5,679.71

Step by Step Solution

1. Step 1: Write the proportion equation
   9,987.08 : 13,780.56 = 5,679.71 : x
2. Step 2: Convert to fraction form
   9,987.08/13,780.56 = 5,679.71/x
3. Step 3: Cross multiply
   9,987.08x = 13,780.56 × 5,679.71
4. Step 4: Simplify right side
   9,987.08x = 78,269,595.32
5. Step 5: Solve for x
   x = 78,269,595.32/9,987.08
6. Step 6: Final answer
   x = 7,837.09