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Finding the Fourth Proportional to 1,320.67, 1,981.38 and 661.75

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Solution

The fourth proportional to 1,320.67, 1,981.38 and 661.75 is: 992.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,320.67 : 1,981.38 = 661.75 : x
  2. Step 2: Convert to fraction form
    1,320.67/1,981.38 = 661.75/x
  3. Step 3: Cross multiply
    1,320.67x = 1,981.38 × 661.75
  4. Step 4: Simplify right side
    1,320.67x = 1,311,177.59
  5. Step 5: Solve for x
    x = 1,311,177.59/1,320.67
  6. Step 6: Final answer
    x = 992.81

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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.