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Finding the Fourth Proportional to 661.60, 992.08 and 387.78

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Solution

The fourth proportional to 661.60, 992.08 and 387.78 is: 581.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.60 : 992.08 = 387.78 : x
  2. Step 2: Convert to fraction form
    661.60/992.08 = 387.78/x
  3. Step 3: Cross multiply
    661.60x = 992.08 × 387.78
  4. Step 4: Simplify right side
    661.60x = 384,708.78
  5. Step 5: Solve for x
    x = 384,708.78/661.60
  6. Step 6: Final answer
    x = 581.48

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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.