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Finding the Fourth Proportional to 861.99, 1,291.37 and 429.45

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Solution

The fourth proportional to 861.99, 1,291.37 and 429.45 is: 643.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.99 : 1,291.37 = 429.45 : x
  2. Step 2: Convert to fraction form
    861.99/1,291.37 = 429.45/x
  3. Step 3: Cross multiply
    861.99x = 1,291.37 × 429.45
  4. Step 4: Simplify right side
    861.99x = 554,576.70
  5. Step 5: Solve for x
    x = 554,576.70/861.99
  6. Step 6: Final answer
    x = 643.37

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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.