Finding the Fourth Proportional to 212,142.51, 318,003.55 and 99,621.30

Step by Step Solution

1. Step 1: Write the proportion equation
   212,142.51 : 318,003.55 = 99,621.30 : x
2. Step 2: Convert to fraction form
   212,142.51/318,003.55 = 99,621.30/x
3. Step 3: Cross multiply
   212,142.51x = 318,003.55 × 99,621.30
4. Step 4: Simplify right side
   212,142.51x = 31,679,927,055.62
5. Step 5: Solve for x
   x = 31,679,927,055.62/212,142.51
6. Step 6: Final answer
   x = 149,333.23