Finding the Fourth Proportional to 1,167.72, 1,611.30 and 643.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,167.72 : 1,611.30 = 643.78 : x
2. Step 2: Convert to fraction form
   1,167.72/1,611.30 = 643.78/x
3. Step 3: Cross multiply
   1,167.72x = 1,611.30 × 643.78
4. Step 4: Simplify right side
   1,167.72x = 1,037,322.71
5. Step 5: Solve for x
   x = 1,037,322.71/1,167.72
6. Step 6: Final answer
   x = 888.33