Finding the Fourth Proportional to 1,091.10, 1,627.28 and 987.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,091.10 : 1,627.28 = 987.42 : x
2. Step 2: Convert to fraction form
   1,091.10/1,627.28 = 987.42/x
3. Step 3: Cross multiply
   1,091.10x = 1,627.28 × 987.42
4. Step 4: Simplify right side
   1,091.10x = 1,606,808.82
5. Step 5: Solve for x
   x = 1,606,808.82/1,091.10
6. Step 6: Final answer
   x = 1,472.65