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Finding the Fourth Proportional to 978.40, 1,349.49 and 628.75

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Solution

The fourth proportional to 978.40, 1,349.49 and 628.75 is: 867.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.40 : 1,349.49 = 628.75 : x
  2. Step 2: Convert to fraction form
    978.40/1,349.49 = 628.75/x
  3. Step 3: Cross multiply
    978.40x = 1,349.49 × 628.75
  4. Step 4: Simplify right side
    978.40x = 848,491.84
  5. Step 5: Solve for x
    x = 848,491.84/978.40
  6. Step 6: Final answer
    x = 867.22

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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.