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Finding the Fourth Proportional to 770.21, 1,062.87 and 420.90

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Solution

The fourth proportional to 770.21, 1,062.87 and 420.90 is: 580.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    770.21 : 1,062.87 = 420.90 : x
  2. Step 2: Convert to fraction form
    770.21/1,062.87 = 420.90/x
  3. Step 3: Cross multiply
    770.21x = 1,062.87 × 420.90
  4. Step 4: Simplify right side
    770.21x = 447,361.98
  5. Step 5: Solve for x
    x = 447,361.98/770.21
  6. Step 6: Final answer
    x = 580.83

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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.