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Finding the Fourth Proportional to 642.70, 886.57 and 390.46

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Solution

The fourth proportional to 642.70, 886.57 and 390.46 is: 538.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.70 : 886.57 = 390.46 : x
  2. Step 2: Convert to fraction form
    642.70/886.57 = 390.46/x
  3. Step 3: Cross multiply
    642.70x = 886.57 × 390.46
  4. Step 4: Simplify right side
    642.70x = 346,170.12
  5. Step 5: Solve for x
    x = 346,170.12/642.70
  6. Step 6: Final answer
    x = 538.62

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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.