Finding the Fourth Proportional to 42,990.13, 64,520.73 and 21,945.72

Step by Step Solution

1. Step 1: Write the proportion equation
   42,990.13 : 64,520.73 = 21,945.72 : x
2. Step 2: Convert to fraction form
   42,990.13/64,520.73 = 21,945.72/x
3. Step 3: Cross multiply
   42,990.13x = 64,520.73 × 21,945.72
4. Step 4: Simplify right side
   42,990.13x = 1,415,953,874.78
5. Step 5: Solve for x
   x = 1,415,953,874.78/42,990.13
6. Step 6: Final answer
   x = 32,936.72