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Finding the Fourth Proportional to 978.81, 1,351.02 and 647.12

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Solution

The fourth proportional to 978.81, 1,351.02 and 647.12 is: 893.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.81 : 1,351.02 = 647.12 : x
  2. Step 2: Convert to fraction form
    978.81/1,351.02 = 647.12/x
  3. Step 3: Cross multiply
    978.81x = 1,351.02 × 647.12
  4. Step 4: Simplify right side
    978.81x = 874,265.31
  5. Step 5: Solve for x
    x = 874,265.31/978.81
  6. Step 6: Final answer
    x = 893.19

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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.