Finding the Fourth Proportional to 42,870.38, 64,322.44 and 13,290.50

Step by Step Solution

1. Step 1: Write the proportion equation
   42,870.38 : 64,322.44 = 13,290.50 : x
2. Step 2: Convert to fraction form
   42,870.38/64,322.44 = 13,290.50/x
3. Step 3: Cross multiply
   42,870.38x = 64,322.44 × 13,290.50
4. Step 4: Simplify right side
   42,870.38x = 854,877,388.82
5. Step 5: Solve for x
   x = 854,877,388.82/42,870.38
6. Step 6: Final answer
   x = 19,940.98