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Finding the Fourth Proportional to 642.84, 887.10 and 421.40

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Solution

The fourth proportional to 642.84, 887.10 and 421.40 is: 581.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.84 : 887.10 = 421.40 : x
  2. Step 2: Convert to fraction form
    642.84/887.10 = 421.40/x
  3. Step 3: Cross multiply
    642.84x = 887.10 × 421.40
  4. Step 4: Simplify right side
    642.84x = 373,826.95
  5. Step 5: Solve for x
    x = 373,826.95/642.84
  6. Step 6: Final answer
    x = 581.53

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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.