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Finding the Fourth Proportional to 390.71, 538.70 and 320.69

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Solution

The fourth proportional to 390.71, 538.70 and 320.69 is: 442.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.71 : 538.70 = 320.69 : x
  2. Step 2: Convert to fraction form
    390.71/538.70 = 320.69/x
  3. Step 3: Cross multiply
    390.71x = 538.70 × 320.69
  4. Step 4: Simplify right side
    390.71x = 172,751.41
  5. Step 5: Solve for x
    x = 172,751.41/390.71
  6. Step 6: Final answer
    x = 442.15

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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.