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Finding the Fourth Proportional to 978.75, 1,346.36 and 938.79

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Solution

The fourth proportional to 978.75, 1,346.36 and 938.79 is: 1,291.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.75 : 1,346.36 = 938.79 : x
  2. Step 2: Convert to fraction form
    978.75/1,346.36 = 938.79/x
  3. Step 3: Cross multiply
    978.75x = 1,346.36 × 938.79
  4. Step 4: Simplify right side
    978.75x = 1,263,944.61
  5. Step 5: Solve for x
    x = 1,263,944.61/978.75
  6. Step 6: Final answer
    x = 1,291.39

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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.