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Finding the Fourth Proportional to 815.85, 1,221.62 and 430.29

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Solution

The fourth proportional to 815.85, 1,221.62 and 430.29 is: 644.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.85 : 1,221.62 = 430.29 : x
  2. Step 2: Convert to fraction form
    815.85/1,221.62 = 430.29/x
  3. Step 3: Cross multiply
    815.85x = 1,221.62 × 430.29
  4. Step 4: Simplify right side
    815.85x = 525,648.72
  5. Step 5: Solve for x
    x = 525,648.72/815.85
  6. Step 6: Final answer
    x = 644.30

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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.