Finding the Fourth Proportional to 13,991.72, 21,064.16 and 12,767

Step by Step Solution

1. Step 1: Write the proportion equation
   13,991.72 : 21,064.16 = 12,767 : x
2. Step 2: Convert to fraction form
   13,991.72/21,064.16 = 12,767/x
3. Step 3: Cross multiply
   13,991.72x = 21,064.16 × 12,767
4. Step 4: Simplify right side
   13,991.72x = 268,926,130.72
5. Step 5: Solve for x
   x = 268,926,130.72/13,991.72
6. Step 6: Final answer
   x = 19,220.38