Finding the Fourth Proportional to 1,678.16, 2,315.69 and 931.95

Step by Step Solution

1. Step 1: Write the proportion equation
   1,678.16 : 2,315.69 = 931.95 : x
2. Step 2: Convert to fraction form
   1,678.16/2,315.69 = 931.95/x
3. Step 3: Cross multiply
   1,678.16x = 2,315.69 × 931.95
4. Step 4: Simplify right side
   1,678.16x = 2,158,102.64
5. Step 5: Solve for x
   x = 2,158,102.64/1,678.16
6. Step 6: Final answer
   x = 1,285.99