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Finding the Fourth Proportional to 947.80, 1,419.06 and 861.20

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Solution

The fourth proportional to 947.80, 1,419.06 and 861.20 is: 1,289.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    947.80 : 1,419.06 = 861.20 : x
  2. Step 2: Convert to fraction form
    947.80/1,419.06 = 861.20/x
  3. Step 3: Cross multiply
    947.80x = 1,419.06 × 861.20
  4. Step 4: Simplify right side
    947.80x = 1,222,094.47
  5. Step 5: Solve for x
    x = 1,222,094.47/947.80
  6. Step 6: Final answer
    x = 1,289.40

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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.