Finding the Fourth Proportional to 1,381.38, 1,903.68 and 987.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,381.38 : 1,903.68 = 987.72 : x
2. Step 2: Convert to fraction form
   1,381.38/1,903.68 = 987.72/x
3. Step 3: Cross multiply
   1,381.38x = 1,903.68 × 987.72
4. Step 4: Simplify right side
   1,381.38x = 1,880,302.81
5. Step 5: Solve for x
   x = 1,880,302.81/1,381.38
6. Step 6: Final answer
   x = 1,361.18