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Finding the Fourth Proportional to 485.40, 669.88 and 288.90

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Solution

The fourth proportional to 485.40, 669.88 and 288.90 is: 398.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.40 : 669.88 = 288.90 : x
  2. Step 2: Convert to fraction form
    485.40/669.88 = 288.90/x
  3. Step 3: Cross multiply
    485.40x = 669.88 × 288.90
  4. Step 4: Simplify right side
    485.40x = 193,528.33
  5. Step 5: Solve for x
    x = 193,528.33/485.40
  6. Step 6: Final answer
    x = 398.70

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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.