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Finding the Fourth Proportional to 861.23, 1,289.93 and 421.81

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Solution

The fourth proportional to 861.23, 1,289.93 and 421.81 is: 631.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.23 : 1,289.93 = 421.81 : x
  2. Step 2: Convert to fraction form
    861.23/1,289.93 = 421.81/x
  3. Step 3: Cross multiply
    861.23x = 1,289.93 × 421.81
  4. Step 4: Simplify right side
    861.23x = 544,100.04
  5. Step 5: Solve for x
    x = 544,100.04/861.23
  6. Step 6: Final answer
    x = 631.77

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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.