Finding the Fourth Proportional to 1,002.21, 1,502.15 and 672.45

Step by Step Solution

1. Step 1: Write the proportion equation
   1,002.21 : 1,502.15 = 672.45 : x
2. Step 2: Convert to fraction form
   1,002.21/1,502.15 = 672.45/x
3. Step 3: Cross multiply
   1,002.21x = 1,502.15 × 672.45
4. Step 4: Simplify right side
   1,002.21x = 1,010,117.41
5. Step 5: Solve for x
   x = 1,010,117.41/1,002.21
6. Step 6: Final answer
   x = 1,007.89