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Finding the Fourth Proportional to 786.47, 1,085.33 and 491.90

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Solution

The fourth proportional to 786.47, 1,085.33 and 491.90 is: 678.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    786.47 : 1,085.33 = 491.90 : x
  2. Step 2: Convert to fraction form
    786.47/1,085.33 = 491.90/x
  3. Step 3: Cross multiply
    786.47x = 1,085.33 × 491.90
  4. Step 4: Simplify right side
    786.47x = 533,872.60
  5. Step 5: Solve for x
    x = 533,872.60/786.47
  6. Step 6: Final answer
    x = 678.83

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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.