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Finding the Fourth Proportional to 980.78, 1,353.20 and 631.67

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Solution

The fourth proportional to 980.78, 1,353.20 and 631.67 is: 871.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    980.78 : 1,353.20 = 631.67 : x
  2. Step 2: Convert to fraction form
    980.78/1,353.20 = 631.67/x
  3. Step 3: Cross multiply
    980.78x = 1,353.20 × 631.67
  4. Step 4: Simplify right side
    980.78x = 854,775.84
  5. Step 5: Solve for x
    x = 854,775.84/980.78
  6. Step 6: Final answer
    x = 871.53

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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.