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Finding the Fourth Proportional to 1,290.20, 1,780.48 and 730.65

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Solution

The fourth proportional to 1,290.20, 1,780.48 and 730.65 is: 1,008.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,290.20 : 1,780.48 = 730.65 : x
  2. Step 2: Convert to fraction form
    1,290.20/1,780.48 = 730.65/x
  3. Step 3: Cross multiply
    1,290.20x = 1,780.48 × 730.65
  4. Step 4: Simplify right side
    1,290.20x = 1,300,915.30
  5. Step 5: Solve for x
    x = 1,300,915.30/1,290.20
  6. Step 6: Final answer
    x = 1,008.31

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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.