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Finding the Fourth Proportional to 978.89, 1,349.47 and 698.64

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Solution

The fourth proportional to 978.89, 1,349.47 and 698.64 is: 963.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.89 : 1,349.47 = 698.64 : x
  2. Step 2: Convert to fraction form
    978.89/1,349.47 = 698.64/x
  3. Step 3: Cross multiply
    978.89x = 1,349.47 × 698.64
  4. Step 4: Simplify right side
    978.89x = 942,793.72
  5. Step 5: Solve for x
    x = 942,793.72/978.89
  6. Step 6: Final answer
    x = 963.13

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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.