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Finding the Fourth Proportional to 390.81, 538.92 and 290.78

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Solution

The fourth proportional to 390.81, 538.92 and 290.78 is: 400.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.81 : 538.92 = 290.78 : x
  2. Step 2: Convert to fraction form
    390.81/538.92 = 290.78/x
  3. Step 3: Cross multiply
    390.81x = 538.92 × 290.78
  4. Step 4: Simplify right side
    390.81x = 156,707.16
  5. Step 5: Solve for x
    x = 156,707.16/390.81
  6. Step 6: Final answer
    x = 400.98

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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.