Finding the Fourth Proportional to 1,090.96, 1,629.86 and 870.16

Step by Step Solution

1. Step 1: Write the proportion equation
   1,090.96 : 1,629.86 = 870.16 : x
2. Step 2: Convert to fraction form
   1,090.96/1,629.86 = 870.16/x
3. Step 3: Cross multiply
   1,090.96x = 1,629.86 × 870.16
4. Step 4: Simplify right side
   1,090.96x = 1,418,238.98
5. Step 5: Solve for x
   x = 1,418,238.98/1,090.96
6. Step 6: Final answer
   x = 1,299.99