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Finding the Fourth Proportional to 987.39, 1,362.57 and 638.28

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Solution

The fourth proportional to 987.39, 1,362.57 and 638.28 is: 880.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.39 : 1,362.57 = 638.28 : x
  2. Step 2: Convert to fraction form
    987.39/1,362.57 = 638.28/x
  3. Step 3: Cross multiply
    987.39x = 1,362.57 × 638.28
  4. Step 4: Simplify right side
    987.39x = 869,701.18
  5. Step 5: Solve for x
    x = 869,701.18/987.39
  6. Step 6: Final answer
    x = 880.81

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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.