Finding the Fourth Proportional to 42,777.60, 64,123.20 and 19,420.80

Step by Step Solution

1. Step 1: Write the proportion equation
   42,777.60 : 64,123.20 = 19,420.80 : x
2. Step 2: Convert to fraction form
   42,777.60/64,123.20 = 19,420.80/x
3. Step 3: Cross multiply
   42,777.60x = 64,123.20 × 19,420.80
4. Step 4: Simplify right side
   42,777.60x = 1,245,323,842.56
5. Step 5: Solve for x
   x = 1,245,323,842.56/42,777.60
6. Step 6: Final answer
   x = 29,111.59