Finding the Fourth Proportional to 42,987.53, 64,490.40 and 12,999.30

Step by Step Solution

1. Step 1: Write the proportion equation
   42,987.53 : 64,490.40 = 12,999.30 : x
2. Step 2: Convert to fraction form
   42,987.53/64,490.40 = 12,999.30/x
3. Step 3: Cross multiply
   42,987.53x = 64,490.40 × 12,999.30
4. Step 4: Simplify right side
   42,987.53x = 838,330,056.72
5. Step 5: Solve for x
   x = 838,330,056.72/42,987.53
6. Step 6: Final answer
   x = 19,501.71