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Finding the Fourth Proportional to 1,321.96, 1,981.02 and 865

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Solution

The fourth proportional to 1,321.96, 1,981.02 and 865 is: 1,296.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,321.96 : 1,981.02 = 865 : x
  2. Step 2: Convert to fraction form
    1,321.96/1,981.02 = 865/x
  3. Step 3: Cross multiply
    1,321.96x = 1,981.02 × 865
  4. Step 4: Simplify right side
    1,321.96x = 1,713,582.30
  5. Step 5: Solve for x
    x = 1,713,582.30/1,321.96
  6. Step 6: Final answer
    x = 1,296.24

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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.