Finding the Fourth Proportional to 42,835.20, 64,215.84 and 20,618

Step by Step Solution

1. Step 1: Write the proportion equation
   42,835.20 : 64,215.84 = 20,618 : x
2. Step 2: Convert to fraction form
   42,835.20/64,215.84 = 20,618/x
3. Step 3: Cross multiply
   42,835.20x = 64,215.84 × 20,618
4. Step 4: Simplify right side
   42,835.20x = 1,324,002,189.12
5. Step 5: Solve for x
   x = 1,324,002,189.12/42,835.20
6. Step 6: Final answer
   x = 30,909.21