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Finding the Fourth Proportional to 989, 1,479.66 and 781.42

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Solution

The fourth proportional to 989, 1,479.66 and 781.42 is: 1,169.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    989 : 1,479.66 = 781.42 : x
  2. Step 2: Convert to fraction form
    989/1,479.66 = 781.42/x
  3. Step 3: Cross multiply
    989x = 1,479.66 × 781.42
  4. Step 4: Simplify right side
    989x = 1,156,235.92
  5. Step 5: Solve for x
    x = 1,156,235.92/989
  6. Step 6: Final answer
    x = 1,169.10

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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.