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Finding the Fourth Proportional to 815.20, 1,222.80 and 609.76

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Solution

The fourth proportional to 815.20, 1,222.80 and 609.76 is: 914.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.20 : 1,222.80 = 609.76 : x
  2. Step 2: Convert to fraction form
    815.20/1,222.80 = 609.76/x
  3. Step 3: Cross multiply
    815.20x = 1,222.80 × 609.76
  4. Step 4: Simplify right side
    815.20x = 745,614.53
  5. Step 5: Solve for x
    x = 745,614.53/815.20
  6. Step 6: Final answer
    x = 914.64

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.