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Finding the Fourth Proportional to 987.40, 1,480.65 and 439.75

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Solution

The fourth proportional to 987.40, 1,480.65 and 439.75 is: 659.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.40 : 1,480.65 = 439.75 : x
  2. Step 2: Convert to fraction form
    987.40/1,480.65 = 439.75/x
  3. Step 3: Cross multiply
    987.40x = 1,480.65 × 439.75
  4. Step 4: Simplify right side
    987.40x = 651,115.84
  5. Step 5: Solve for x
    x = 651,115.84/987.40
  6. Step 6: Final answer
    x = 659.42

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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.