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Finding the Fourth Proportional to 390.40, 538.02 and 307.42

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Solution

The fourth proportional to 390.40, 538.02 and 307.42 is: 423.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.40 : 538.02 = 307.42 : x
  2. Step 2: Convert to fraction form
    390.40/538.02 = 307.42/x
  3. Step 3: Cross multiply
    390.40x = 538.02 × 307.42
  4. Step 4: Simplify right side
    390.40x = 165,398.11
  5. Step 5: Solve for x
    x = 165,398.11/390.40
  6. Step 6: Final answer
    x = 423.66

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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.