Finding the Fourth Proportional to 30,870.21, 42,600 and 18,123.18

Step by Step Solution

1. Step 1: Write the proportion equation
   30,870.21 : 42,600 = 18,123.18 : x
2. Step 2: Convert to fraction form
   30,870.21/42,600 = 18,123.18/x
3. Step 3: Cross multiply
   30,870.21x = 42,600 × 18,123.18
4. Step 4: Simplify right side
   30,870.21x = 772,047,468
5. Step 5: Solve for x
   x = 772,047,468/30,870.21
6. Step 6: Final answer
   x = 25,009.47