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Finding the Fourth Proportional to 485.21, 669.65 and 288.72

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Solution

The fourth proportional to 485.21, 669.65 and 288.72 is: 398.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.21 : 669.65 = 288.72 : x
  2. Step 2: Convert to fraction form
    485.21/669.65 = 288.72/x
  3. Step 3: Cross multiply
    485.21x = 669.65 × 288.72
  4. Step 4: Simplify right side
    485.21x = 193,342.19
  5. Step 5: Solve for x
    x = 193,342.19/485.21
  6. Step 6: Final answer
    x = 398.47

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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.