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Finding the Fourth Proportional to 988.39, 1,363.95 and 639.28

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Solution

The fourth proportional to 988.39, 1,363.95 and 639.28 is: 882.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    988.39 : 1,363.95 = 639.28 : x
  2. Step 2: Convert to fraction form
    988.39/1,363.95 = 639.28/x
  3. Step 3: Cross multiply
    988.39x = 1,363.95 × 639.28
  4. Step 4: Simplify right side
    988.39x = 871,945.96
  5. Step 5: Solve for x
    x = 871,945.96/988.39
  6. Step 6: Final answer
    x = 882.19

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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.