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Finding the Fourth Proportional to 979.56, 1,351.85 and 647.40

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Solution

The fourth proportional to 979.56, 1,351.85 and 647.40 is: 893.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    979.56 : 1,351.85 = 647.40 : x
  2. Step 2: Convert to fraction form
    979.56/1,351.85 = 647.40/x
  3. Step 3: Cross multiply
    979.56x = 1,351.85 × 647.40
  4. Step 4: Simplify right side
    979.56x = 875,187.69
  5. Step 5: Solve for x
    x = 875,187.69/979.56
  6. Step 6: Final answer
    x = 893.45

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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.