Finding the Fourth Proportional to 21,728.86, 29,984.79 and 13,345.18

Step by Step Solution

1. Step 1: Write the proportion equation
   21,728.86 : 29,984.79 = 13,345.18 : x
2. Step 2: Convert to fraction form
   21,728.86/29,984.79 = 13,345.18/x
3. Step 3: Cross multiply
   21,728.86x = 29,984.79 × 13,345.18
4. Step 4: Simplify right side
   21,728.86x = 400,152,419.81
5. Step 5: Solve for x
   x = 400,152,419.81/21,728.86
6. Step 6: Final answer
   x = 18,415.71