Finding the Fourth Proportional to 1,167.91, 1,611.71 and 643.94

Step by Step Solution

1. Step 1: Write the proportion equation
   1,167.91 : 1,611.71 = 643.94 : x
2. Step 2: Convert to fraction form
   1,167.91/1,611.71 = 643.94/x
3. Step 3: Cross multiply
   1,167.91x = 1,611.71 × 643.94
4. Step 4: Simplify right side
   1,167.91x = 1,037,844.54
5. Step 5: Solve for x
   x = 1,037,844.54/1,167.91
6. Step 6: Final answer
   x = 888.63