Finding the Fourth Proportional to 1,175.10, 1,621.59 and 643.98

Step by Step Solution

1. Step 1: Write the proportion equation
   1,175.10 : 1,621.59 = 643.98 : x
2. Step 2: Convert to fraction form
   1,175.10/1,621.59 = 643.98/x
3. Step 3: Cross multiply
   1,175.10x = 1,621.59 × 643.98
4. Step 4: Simplify right side
   1,175.10x = 1,044,271.53
5. Step 5: Solve for x
   x = 1,044,271.53/1,175.10
6. Step 6: Final answer
   x = 888.67