Finding the Fourth Proportional to 1,111.42, 1,667.31 and 380.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.42 : 1,667.31 = 380.81 : x
2. Step 2: Convert to fraction form
   1,111.42/1,667.31 = 380.81/x
3. Step 3: Cross multiply
   1,111.42x = 1,667.31 × 380.81
4. Step 4: Simplify right side
   1,111.42x = 634,928.32
5. Step 5: Solve for x
   x = 634,928.32/1,111.42
6. Step 6: Final answer
   x = 571.28