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Finding the Fourth Proportional to 661.20, 991.80 and 430.35

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Solution

The fourth proportional to 661.20, 991.80 and 430.35 is: 645.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.20 : 991.80 = 430.35 : x
  2. Step 2: Convert to fraction form
    661.20/991.80 = 430.35/x
  3. Step 3: Cross multiply
    661.20x = 991.80 × 430.35
  4. Step 4: Simplify right side
    661.20x = 426,821.13
  5. Step 5: Solve for x
    x = 426,821.13/661.20
  6. Step 6: Final answer
    x = 645.53

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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.