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Finding the Fourth Proportional to 870.69, 1,305.45 and 408.21

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Solution

The fourth proportional to 870.69, 1,305.45 and 408.21 is: 612.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    870.69 : 1,305.45 = 408.21 : x
  2. Step 2: Convert to fraction form
    870.69/1,305.45 = 408.21/x
  3. Step 3: Cross multiply
    870.69x = 1,305.45 × 408.21
  4. Step 4: Simplify right side
    870.69x = 532,897.74
  5. Step 5: Solve for x
    x = 532,897.74/870.69
  6. Step 6: Final answer
    x = 612.04

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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.