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Finding the Fourth Proportional to 679.68, 1,019.76 and 387.48

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Solution

The fourth proportional to 679.68, 1,019.76 and 387.48 is: 581.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    679.68 : 1,019.76 = 387.48 : x
  2. Step 2: Convert to fraction form
    679.68/1,019.76 = 387.48/x
  3. Step 3: Cross multiply
    679.68x = 1,019.76 × 387.48
  4. Step 4: Simplify right side
    679.68x = 395,136.60
  5. Step 5: Solve for x
    x = 395,136.60/679.68
  6. Step 6: Final answer
    x = 581.36

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.