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Finding the Fourth Proportional to 771.21, 1,064.40 and 491.56

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Solution

The fourth proportional to 771.21, 1,064.40 and 491.56 is: 678.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    771.21 : 1,064.40 = 491.56 : x
  2. Step 2: Convert to fraction form
    771.21/1,064.40 = 491.56/x
  3. Step 3: Cross multiply
    771.21x = 1,064.40 × 491.56
  4. Step 4: Simplify right side
    771.21x = 523,213.80
  5. Step 5: Solve for x
    x = 523,213.80/771.21
  6. Step 6: Final answer
    x = 678.43

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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.