Finding the Fourth Proportional to 42,970.68, 64,467.20 and 13,389

Step by Step Solution

1. Step 1: Write the proportion equation
   42,970.68 : 64,467.20 = 13,389 : x
2. Step 2: Convert to fraction form
   42,970.68/64,467.20 = 13,389/x
3. Step 3: Cross multiply
   42,970.68x = 64,467.20 × 13,389
4. Step 4: Simplify right side
   42,970.68x = 863,151,340.80
5. Step 5: Solve for x
   x = 863,151,340.80/42,970.68
6. Step 6: Final answer
   x = 20,086.98