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Finding the Fourth Proportional to 485.40, 669.69 and 310.85

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Solution

The fourth proportional to 485.40, 669.69 and 310.85 is: 428.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.40 : 669.69 = 310.85 : x
  2. Step 2: Convert to fraction form
    485.40/669.69 = 310.85/x
  3. Step 3: Cross multiply
    485.40x = 669.69 × 310.85
  4. Step 4: Simplify right side
    485.40x = 208,173.14
  5. Step 5: Solve for x
    x = 208,173.14/485.40
  6. Step 6: Final answer
    x = 428.87

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.