Finding the Fourth Proportional to 42,777.17, 64,169.18 and 12,789.21

Step by Step Solution

1. Step 1: Write the proportion equation
   42,777.17 : 64,169.18 = 12,789.21 : x
2. Step 2: Convert to fraction form
   42,777.17/64,169.18 = 12,789.21/x
3. Step 3: Cross multiply
   42,777.17x = 64,169.18 × 12,789.21
4. Step 4: Simplify right side
   42,777.17x = 820,673,118.55
5. Step 5: Solve for x
   x = 820,673,118.55/42,777.17
6. Step 6: Final answer
   x = 19,184.84