Finding the Fourth Proportional to 42,840.32, 64,260.69 and 13,258.31

Step by Step Solution

1. Step 1: Write the proportion equation
   42,840.32 : 64,260.69 = 13,258.31 : x
2. Step 2: Convert to fraction form
   42,840.32/64,260.69 = 13,258.31/x
3. Step 3: Cross multiply
   42,840.32x = 64,260.69 × 13,258.31
4. Step 4: Simplify right side
   42,840.32x = 851,988,082.54
5. Step 5: Solve for x
   x = 851,988,082.54/42,840.32
6. Step 6: Final answer
   x = 19,887.53