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Finding the Fourth Proportional to 978.75, 1,349.46 and 646.43

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Solution

The fourth proportional to 978.75, 1,349.46 and 646.43 is: 891.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.75 : 1,349.46 = 646.43 : x
  2. Step 2: Convert to fraction form
    978.75/1,349.46 = 646.43/x
  3. Step 3: Cross multiply
    978.75x = 1,349.46 × 646.43
  4. Step 4: Simplify right side
    978.75x = 872,324.68
  5. Step 5: Solve for x
    x = 872,324.68/978.75
  6. Step 6: Final answer
    x = 891.26

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Double scale
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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.