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Finding the Fourth Proportional to 861.20, 1,291.80 and 846.80

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Solution

The fourth proportional to 861.20, 1,291.80 and 846.80 is: 1,270.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.20 : 1,291.80 = 846.80 : x
  2. Step 2: Convert to fraction form
    861.20/1,291.80 = 846.80/x
  3. Step 3: Cross multiply
    861.20x = 1,291.80 × 846.80
  4. Step 4: Simplify right side
    861.20x = 1,093,896.24
  5. Step 5: Solve for x
    x = 1,093,896.24/861.20
  6. Step 6: Final answer
    x = 1,270.20

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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.