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Finding the Fourth Proportional to 981, 1,353.78 and 631.74

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Solution

The fourth proportional to 981, 1,353.78 and 631.74 is: 871.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    981 : 1,353.78 = 631.74 : x
  2. Step 2: Convert to fraction form
    981/1,353.78 = 631.74/x
  3. Step 3: Cross multiply
    981x = 1,353.78 × 631.74
  4. Step 4: Simplify right side
    981x = 855,236.98
  5. Step 5: Solve for x
    x = 855,236.98/981
  6. Step 6: Final answer
    x = 871.80

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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.