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Finding the Fourth Proportional to 390.69, 538.85 and 280.53

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Solution

The fourth proportional to 390.69, 538.85 and 280.53 is: 386.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.69 : 538.85 = 280.53 : x
  2. Step 2: Convert to fraction form
    390.69/538.85 = 280.53/x
  3. Step 3: Cross multiply
    390.69x = 538.85 × 280.53
  4. Step 4: Simplify right side
    390.69x = 151,164.29
  5. Step 5: Solve for x
    x = 151,164.29/390.69
  6. Step 6: Final answer
    x = 386.92

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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.