Finding the Fourth Proportional to 2,167.51, 2,991.16 and 1,172.78

Step by Step Solution

1. Step 1: Write the proportion equation
   2,167.51 : 2,991.16 = 1,172.78 : x
2. Step 2: Convert to fraction form
   2,167.51/2,991.16 = 1,172.78/x
3. Step 3: Cross multiply
   2,167.51x = 2,991.16 × 1,172.78
4. Step 4: Simplify right side
   2,167.51x = 3,507,970.35
5. Step 5: Solve for x
   x = 3,507,970.35/2,167.51
6. Step 6: Final answer
   x = 1,618.43