Finding the Fourth Proportional to 1,390.42, 1,918.74 and 769.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.42 : 1,918.74 = 769.42 : x
2. Step 2: Convert to fraction form
   1,390.42/1,918.74 = 769.42/x
3. Step 3: Cross multiply
   1,390.42x = 1,918.74 × 769.42
4. Step 4: Simplify right side
   1,390.42x = 1,476,316.93
5. Step 5: Solve for x
   x = 1,476,316.93/1,390.42
6. Step 6: Final answer
   x = 1,061.78