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Finding the Fourth Proportional to 987.12, 1,480.45 and 439

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Solution

The fourth proportional to 987.12, 1,480.45 and 439 is: 658.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.12 : 1,480.45 = 439 : x
  2. Step 2: Convert to fraction form
    987.12/1,480.45 = 439/x
  3. Step 3: Cross multiply
    987.12x = 1,480.45 × 439
  4. Step 4: Simplify right side
    987.12x = 649,916.45
  5. Step 5: Solve for x
    x = 649,916.45/987.12
  6. Step 6: Final answer
    x = 658.40

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1.5x scale

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.