Finding the Fourth Proportional to 1,111.77, 1,533.81 and 639.51

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.77 : 1,533.81 = 639.51 : x
2. Step 2: Convert to fraction form
   1,111.77/1,533.81 = 639.51/x
3. Step 3: Cross multiply
   1,111.77x = 1,533.81 × 639.51
4. Step 4: Simplify right side
   1,111.77x = 980,886.83
5. Step 5: Solve for x
   x = 980,886.83/1,111.77
6. Step 6: Final answer
   x = 882.27