Finding the Fourth Proportional to 42,875.60, 64,320.21 and 13,287.31

Step by Step Solution

1. Step 1: Write the proportion equation
   42,875.60 : 64,320.21 = 13,287.31 : x
2. Step 2: Convert to fraction form
   42,875.60/64,320.21 = 13,287.31/x
3. Step 3: Cross multiply
   42,875.60x = 64,320.21 × 13,287.31
4. Step 4: Simplify right side
   42,875.60x = 854,642,408.73
5. Step 5: Solve for x
   x = 854,642,408.73/42,875.60
6. Step 6: Final answer
   x = 19,933.07