Finding the Fourth Proportional to 21,936.81, 30,272.80 and 12,378.72

Step by Step Solution

1. Step 1: Write the proportion equation
   21,936.81 : 30,272.80 = 12,378.72 : x
2. Step 2: Convert to fraction form
   21,936.81/30,272.80 = 12,378.72/x
3. Step 3: Cross multiply
   21,936.81x = 30,272.80 × 12,378.72
4. Step 4: Simplify right side
   21,936.81x = 374,738,514.82
5. Step 5: Solve for x
   x = 374,738,514.82/21,936.81
6. Step 6: Final answer
   x = 17,082.63