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Finding the Fourth Proportional to 861.55, 1,291.75 and 313.67

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Solution

The fourth proportional to 861.55, 1,291.75 and 313.67 is: 470.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.55 : 1,291.75 = 313.67 : x
  2. Step 2: Convert to fraction form
    861.55/1,291.75 = 313.67/x
  3. Step 3: Cross multiply
    861.55x = 1,291.75 × 313.67
  4. Step 4: Simplify right side
    861.55x = 405,183.22
  5. Step 5: Solve for x
    x = 405,183.22/861.55
  6. Step 6: Final answer
    x = 470.30

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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.