Finding the Fourth Proportional to 42,987.77, 64,494.47 and 20,515.32

Step by Step Solution

1. Step 1: Write the proportion equation
   42,987.77 : 64,494.47 = 20,515.32 : x
2. Step 2: Convert to fraction form
   42,987.77/64,494.47 = 20,515.32/x
3. Step 3: Cross multiply
   42,987.77x = 64,494.47 × 20,515.32
4. Step 4: Simplify right side
   42,987.77x = 1,323,124,741.57
5. Step 5: Solve for x
   x = 1,323,124,741.57/42,987.77
6. Step 6: Final answer
   x = 30,779.10