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Finding the Fourth Proportional to 1,290.84, 1,780.66 and 817.88

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Solution

The fourth proportional to 1,290.84, 1,780.66 and 817.88 is: 1,128.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,290.84 : 1,780.66 = 817.88 : x
  2. Step 2: Convert to fraction form
    1,290.84/1,780.66 = 817.88/x
  3. Step 3: Cross multiply
    1,290.84x = 1,780.66 × 817.88
  4. Step 4: Simplify right side
    1,290.84x = 1,456,366.20
  5. Step 5: Solve for x
    x = 1,456,366.20/1,290.84
  6. Step 6: Final answer
    x = 1,128.23

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.