Finding the Fourth Proportional to 42,770, 64,181.74 and 20,585.72

Step by Step Solution

1. Step 1: Write the proportion equation
   42,770 : 64,181.74 = 20,585.72 : x
2. Step 2: Convert to fraction form
   42,770/64,181.74 = 20,585.72/x
3. Step 3: Cross multiply
   42,770x = 64,181.74 × 20,585.72
4. Step 4: Simplify right side
   42,770x = 1,321,227,328.75
5. Step 5: Solve for x
   x = 1,321,227,328.75/42,770
6. Step 6: Final answer
   x = 30,891.45