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Finding the Fourth Proportional to 659.80, 989.70 and 611.80

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Solution

The fourth proportional to 659.80, 989.70 and 611.80 is: 917.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    659.80 : 989.70 = 611.80 : x
  2. Step 2: Convert to fraction form
    659.80/989.70 = 611.80/x
  3. Step 3: Cross multiply
    659.80x = 989.70 × 611.80
  4. Step 4: Simplify right side
    659.80x = 605,498.46
  5. Step 5: Solve for x
    x = 605,498.46/659.80
  6. Step 6: Final answer
    x = 917.70

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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.