Finding the Fourth Proportional to 42,690, 64,040.12 and 13,103.96

Step by Step Solution

1. Step 1: Write the proportion equation
   42,690 : 64,040.12 = 13,103.96 : x
2. Step 2: Convert to fraction form
   42,690/64,040.12 = 13,103.96/x
3. Step 3: Cross multiply
   42,690x = 64,040.12 × 13,103.96
4. Step 4: Simplify right side
   42,690x = 839,179,170.88
5. Step 5: Solve for x
   x = 839,179,170.88/42,690
6. Step 6: Final answer
   x = 19,657.51