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Finding the Fourth Proportional to 485.70, 669.90 and 310.95

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Solution

The fourth proportional to 485.70, 669.90 and 310.95 is: 428.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.70 : 669.90 = 310.95 : x
  2. Step 2: Convert to fraction form
    485.70/669.90 = 310.95/x
  3. Step 3: Cross multiply
    485.70x = 669.90 × 310.95
  4. Step 4: Simplify right side
    485.70x = 208,305.41
  5. Step 5: Solve for x
    x = 208,305.41/485.70
  6. Step 6: Final answer
    x = 428.88

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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.