Finding the Fourth Proportional to 61,200.05, 91,779.28 and 21,209.72

Step by Step Solution

1. Step 1: Write the proportion equation
   61,200.05 : 91,779.28 = 21,209.72 : x
2. Step 2: Convert to fraction form
   61,200.05/91,779.28 = 21,209.72/x
3. Step 3: Cross multiply
   61,200.05x = 91,779.28 × 21,209.72
4. Step 4: Simplify right side
   61,200.05x = 1,946,612,830.60
5. Step 5: Solve for x
   x = 1,946,612,830.60/61,200.05
6. Step 6: Final answer
   x = 31,807.37