Finding the Fourth Proportional to 42,789.64, 64,160.94 and 13,199.32

Step by Step Solution

1. Step 1: Write the proportion equation
   42,789.64 : 64,160.94 = 13,199.32 : x
2. Step 2: Convert to fraction form
   42,789.64/64,160.94 = 13,199.32/x
3. Step 3: Cross multiply
   42,789.64x = 64,160.94 × 13,199.32
4. Step 4: Simplify right side
   42,789.64x = 846,880,778.56
5. Step 5: Solve for x
   x = 846,880,778.56/42,789.64
6. Step 6: Final answer
   x = 19,791.72