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Finding the Fourth Proportional to 903.71, 1,355.69 and 318.78

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Solution

The fourth proportional to 903.71, 1,355.69 and 318.78 is: 478.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    903.71 : 1,355.69 = 318.78 : x
  2. Step 2: Convert to fraction form
    903.71/1,355.69 = 318.78/x
  3. Step 3: Cross multiply
    903.71x = 1,355.69 × 318.78
  4. Step 4: Simplify right side
    903.71x = 432,167.66
  5. Step 5: Solve for x
    x = 432,167.66/903.71
  6. Step 6: Final answer
    x = 478.21

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.