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Finding the Fourth Proportional to 987.57, 1,362.85 and 689.25

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Solution

The fourth proportional to 987.57, 1,362.85 and 689.25 is: 951.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.57 : 1,362.85 = 689.25 : x
  2. Step 2: Convert to fraction form
    987.57/1,362.85 = 689.25/x
  3. Step 3: Cross multiply
    987.57x = 1,362.85 × 689.25
  4. Step 4: Simplify right side
    987.57x = 939,337.55
  5. Step 5: Solve for x
    x = 939,337.55/987.57
  6. Step 6: Final answer
    x = 951.17

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.