Finding the Fourth Proportional to 15,288.18, 21,106.89 and 9,991.86

Step by Step Solution

1. Step 1: Write the proportion equation
   15,288.18 : 21,106.89 = 9,991.86 : x
2. Step 2: Convert to fraction form
   15,288.18/21,106.89 = 9,991.86/x
3. Step 3: Cross multiply
   15,288.18x = 21,106.89 × 9,991.86
4. Step 4: Simplify right side
   15,288.18x = 210,897,089.92
5. Step 5: Solve for x
   x = 210,897,089.92/15,288.18
6. Step 6: Final answer
   x = 13,794.78