Finding the Fourth Proportional to 1,019.46, 1,405.71 and 645.99

Step by Step Solution

1. Step 1: Write the proportion equation
   1,019.46 : 1,405.71 = 645.99 : x
2. Step 2: Convert to fraction form
   1,019.46/1,405.71 = 645.99/x
3. Step 3: Cross multiply
   1,019.46x = 1,405.71 × 645.99
4. Step 4: Simplify right side
   1,019.46x = 908,074.60
5. Step 5: Solve for x
   x = 908,074.60/1,019.46
6. Step 6: Final answer
   x = 890.74