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Finding the Fourth Proportional to 987.19, 1,480.95 and 431.87

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Solution

The fourth proportional to 987.19, 1,480.95 and 431.87 is: 647.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.19 : 1,480.95 = 431.87 : x
  2. Step 2: Convert to fraction form
    987.19/1,480.95 = 431.87/x
  3. Step 3: Cross multiply
    987.19x = 1,480.95 × 431.87
  4. Step 4: Simplify right side
    987.19x = 639,570.47
  5. Step 5: Solve for x
    x = 639,570.47/987.19
  6. Step 6: Final answer
    x = 647.87

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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.