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Finding the Fourth Proportional to 485.50, 669.80 and 319.80

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Solution

The fourth proportional to 485.50, 669.80 and 319.80 is: 441.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.50 : 669.80 = 319.80 : x
  2. Step 2: Convert to fraction form
    485.50/669.80 = 319.80/x
  3. Step 3: Cross multiply
    485.50x = 669.80 × 319.80
  4. Step 4: Simplify right side
    485.50x = 214,202.04
  5. Step 5: Solve for x
    x = 214,202.04/485.50
  6. Step 6: Final answer
    x = 441.20

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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.