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Finding the Fourth Proportional to 642.98, 886.89 and 421.70

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Solution

The fourth proportional to 642.98, 886.89 and 421.70 is: 581.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.98 : 886.89 = 421.70 : x
  2. Step 2: Convert to fraction form
    642.98/886.89 = 421.70/x
  3. Step 3: Cross multiply
    642.98x = 886.89 × 421.70
  4. Step 4: Simplify right side
    642.98x = 373,997.08
  5. Step 5: Solve for x
    x = 373,997.08/642.98
  6. Step 6: Final answer
    x = 581.67

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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.