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Finding the Fourth Proportional to 978.76, 1,350.64 and 717.88

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Solution

The fourth proportional to 978.76, 1,350.64 and 717.88 is: 990.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.76 : 1,350.64 = 717.88 : x
  2. Step 2: Convert to fraction form
    978.76/1,350.64 = 717.88/x
  3. Step 3: Cross multiply
    978.76x = 1,350.64 × 717.88
  4. Step 4: Simplify right side
    978.76x = 969,597.44
  5. Step 5: Solve for x
    x = 969,597.44/978.76
  6. Step 6: Final answer
    x = 990.64

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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.