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Finding the Fourth Proportional to 978.32, 1,349.11 and 646.36

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Solution

The fourth proportional to 978.32, 1,349.11 and 646.36 is: 891.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.32 : 1,349.11 = 646.36 : x
  2. Step 2: Convert to fraction form
    978.32/1,349.11 = 646.36/x
  3. Step 3: Cross multiply
    978.32x = 1,349.11 × 646.36
  4. Step 4: Simplify right side
    978.32x = 872,010.74
  5. Step 5: Solve for x
    x = 872,010.74/978.32
  6. Step 6: Final answer
    x = 891.33

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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.