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Finding the Fourth Proportional to 939.60, 1,405.40 and 842.80

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Solution

The fourth proportional to 939.60, 1,405.40 and 842.80 is: 1,260.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.60 : 1,405.40 = 842.80 : x
  2. Step 2: Convert to fraction form
    939.60/1,405.40 = 842.80/x
  3. Step 3: Cross multiply
    939.60x = 1,405.40 × 842.80
  4. Step 4: Simplify right side
    939.60x = 1,184,471.12
  5. Step 5: Solve for x
    x = 1,184,471.12/939.60
  6. Step 6: Final answer
    x = 1,260.61

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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.