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Finding the Fourth Proportional to 861.66, 1,290.78 and 631.05

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Solution

The fourth proportional to 861.66, 1,290.78 and 631.05 is: 945.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.66 : 1,290.78 = 631.05 : x
  2. Step 2: Convert to fraction form
    861.66/1,290.78 = 631.05/x
  3. Step 3: Cross multiply
    861.66x = 1,290.78 × 631.05
  4. Step 4: Simplify right side
    861.66x = 814,546.72
  5. Step 5: Solve for x
    x = 814,546.72/861.66
  6. Step 6: Final answer
    x = 945.32

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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.