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Finding the Fourth Proportional to 642.16, 885.90 and 420.76

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Solution

The fourth proportional to 642.16, 885.90 and 420.76 is: 580.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.16 : 885.90 = 420.76 : x
  2. Step 2: Convert to fraction form
    642.16/885.90 = 420.76/x
  3. Step 3: Cross multiply
    642.16x = 885.90 × 420.76
  4. Step 4: Simplify right side
    642.16x = 372,751.28
  5. Step 5: Solve for x
    x = 372,751.28/642.16
  6. Step 6: Final answer
    x = 580.46

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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.