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Finding the Fourth Proportional to 389.76, 538.56 and 320.64

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Solution

The fourth proportional to 389.76, 538.56 and 320.64 is: 443.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    389.76 : 538.56 = 320.64 : x
  2. Step 2: Convert to fraction form
    389.76/538.56 = 320.64/x
  3. Step 3: Cross multiply
    389.76x = 538.56 × 320.64
  4. Step 4: Simplify right side
    389.76x = 172,683.88
  5. Step 5: Solve for x
    x = 172,683.88/389.76
  6. Step 6: Final answer
    x = 443.05

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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.