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Finding the Fourth Proportional to 680.74, 939.40 and 491.74

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Solution

The fourth proportional to 680.74, 939.40 and 491.74 is: 678.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.74 : 939.40 = 491.74 : x
  2. Step 2: Convert to fraction form
    680.74/939.40 = 491.74/x
  3. Step 3: Cross multiply
    680.74x = 939.40 × 491.74
  4. Step 4: Simplify right side
    680.74x = 461,936.98
  5. Step 5: Solve for x
    x = 461,936.98/680.74
  6. Step 6: Final answer
    x = 678.58

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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.