Finding the Fourth Proportional to 1,111.21, 1,666.29 and 417.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.21 : 1,666.29 = 417.34 : x
2. Step 2: Convert to fraction form
   1,111.21/1,666.29 = 417.34/x
3. Step 3: Cross multiply
   1,111.21x = 1,666.29 × 417.34
4. Step 4: Simplify right side
   1,111.21x = 695,409.47
5. Step 5: Solve for x
   x = 695,409.47/1,111.21
6. Step 6: Final answer
   x = 625.81