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Finding the Fourth Proportional to 1,318.74, 1,978.79 and 660.71

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Solution

The fourth proportional to 1,318.74, 1,978.79 and 660.71 is: 991.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,318.74 : 1,978.79 = 660.71 : x
  2. Step 2: Convert to fraction form
    1,318.74/1,978.79 = 660.71/x
  3. Step 3: Cross multiply
    1,318.74x = 1,978.79 × 660.71
  4. Step 4: Simplify right side
    1,318.74x = 1,307,393.14
  5. Step 5: Solve for x
    x = 1,307,393.14/1,318.74
  6. Step 6: Final answer
    x = 991.40

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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.