Finding the Fourth Proportional to 42,708.21, 64,068.45 and 13,128.53

Step by Step Solution

1. Step 1: Write the proportion equation
   42,708.21 : 64,068.45 = 13,128.53 : x
2. Step 2: Convert to fraction form
   42,708.21/64,068.45 = 13,128.53/x
3. Step 3: Cross multiply
   42,708.21x = 64,068.45 × 13,128.53
4. Step 4: Simplify right side
   42,708.21x = 841,124,678.82
5. Step 5: Solve for x
   x = 841,124,678.82/42,708.21
6. Step 6: Final answer
   x = 19,694.68