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Finding the Fourth Proportional to 947.20, 1,420.80 and 838.40

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Solution

The fourth proportional to 947.20, 1,420.80 and 838.40 is: 1,257.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    947.20 : 1,420.80 = 838.40 : x
  2. Step 2: Convert to fraction form
    947.20/1,420.80 = 838.40/x
  3. Step 3: Cross multiply
    947.20x = 1,420.80 × 838.40
  4. Step 4: Simplify right side
    947.20x = 1,191,198.72
  5. Step 5: Solve for x
    x = 1,191,198.72/947.20
  6. Step 6: Final answer
    x = 1,257.60

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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.