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Finding the Fourth Proportional to 642.13, 885.70 and 620.70

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Solution

The fourth proportional to 642.13, 885.70 and 620.70 is: 856.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.13 : 885.70 = 620.70 : x
  2. Step 2: Convert to fraction form
    642.13/885.70 = 620.70/x
  3. Step 3: Cross multiply
    642.13x = 885.70 × 620.70
  4. Step 4: Simplify right side
    642.13x = 549,753.99
  5. Step 5: Solve for x
    x = 549,753.99/642.13
  6. Step 6: Final answer
    x = 856.14

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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.