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Finding the Fourth Proportional to 661.55, 991.69 and 387.59

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Solution

The fourth proportional to 661.55, 991.69 and 387.59 is: 581.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.55 : 991.69 = 387.59 : x
  2. Step 2: Convert to fraction form
    661.55/991.69 = 387.59/x
  3. Step 3: Cross multiply
    661.55x = 991.69 × 387.59
  4. Step 4: Simplify right side
    661.55x = 384,369.13
  5. Step 5: Solve for x
    x = 384,369.13/661.55
  6. Step 6: Final answer
    x = 581.01

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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.